1 REVISION 1

2 Love is in the Earth: a review of tellurium (bio)geochemistry in Earth

3 surface environments

4

5 O.P. Missen a,b,*, R. Ram a, S.J. Mills b, B. Etschmann a, F. Reith c,d , J. Shuster c,d, D.J. Smith e,

6 J. Brugger a,*

7

8 a School of Earth, Atmosphere and Environment, 9 Rainforest Walk, Monash University,

9 Clayton 3800, Victoria, Australia

10 b Geosciences, Museums Victoria, GPO Box 666, Melbourne 3001, Victoria, Australia

11 c School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia

12 d CSIRO Land and Water, Contaminant Chemistry and Ecotoxicology, PMB2, Glen Osmond,

13 SA 5064, Australia

14 e School of Geography, Geology & the Environment, University of Leicester, Leicester, UK

15

16 *Corresponding authors’ e-mails: [email protected], [email protected]

17

18

19 Keywords: Tellurium cycling, environments, (bio)geochemistry, mobility, mineralogy

20

21 22 ABSTRACT

23 Tellurium (Te) is a rare metalloid in the chalcogen group of the Periodic Table. Tellurium is

24 regularly listed as a critical raw material both due to its increased use in the solar industry, and

25 to the dependence on other commodities in its supply chain. A thorough understanding of the

26 geo(bio)chemistry of Te in surface environments is fundamental for supporting the search for

27 future sources of Te (geochemical exploration); developing innovative processing techniques

28 for extracting Te; and quantifying the environmental risks associated with rapidly increasing

29 anthropogenic uses. The present work links existing research in inorganic Te geochemistry and

30 mineralogy with the bio(geo)chemical and biological literature towards developing an

31 integrated Te cycling model.

32 Although average crustal rocks contain only a few µg/kg of Te, hydrothermal fluids and

33 vapours are able to enrich Te to levels in excess of mg/kg. Tellurium is currently recovered as

34 a by-product of base-metal mining; in these deposits, it occurs mainly in common sulphides

35 substituting for sulphur. Extreme Te enrichment (up to wt.%) is found in association with the

36 precious metals Au and Ag in the form of telluride and sulphosalt minerals. Tellurium also

37 forms a large variety of oxygen-containing secondary minerals as a result of weathering of Te-

38 containing ores in (near-)surface environments. Anthropogenic activities introduce significant

39 amounts of Te into surficial environments, both through processing materials that contain

40 minor Te, and through breakdown of used Te-containing materials. Additionally, radioactive

41 132Te is produced in nuclear reactors, and can contaminate surrounding and distal environments.

42 Environmental contamination of Te poses concern to organisms due to the acute toxicity of

43 some Te compounds, especially the soluble tellurite and tellurate anions. A small percentage

44 of microorganisms, however, are able to tolerate elevated levels of Te by detoxifying it through

45 precipitation or volatilisation. Bioaccumulation of Te compounds can occur in some plants of 46 the garlic family. A variety of interlinked processes govern Te environmental chemistry,

47 linking them into a cycle which encompasses both inorganic and organic processes. The Te

48 cycle in surface environments incorporates (oxidative) dissolution of Te from primary ore

49 minerals, inorganic precipitation and redissolution processes in which secondary minerals are

50 formed, and bioreductive reprecipitation and volatilisation processes governed mainly by

51 microbes. Our integrated Te cycling model highlights the interplay between anthropogenic,

52 geochemical and biogeochemical processes on the distribution and mobility of Te in surface

53 environments.

54 HIGHLIGHTS

55 • Tellurium has a complex environmental geochemistry 56 • The many modes of Te bonding govern its surface behaviour 57 • Outcropping Te deposits are an analogue for anthropogenic contamination 58 • We propose a cycling model for tellurium in surface environments 59 • We highlight future areas for tellurium biogeochemical research

60 TABLE OF CONTENTS

61 1. Introduction 62 2. Physical and chemical properties of tellurium 63 3. Tellurium mineralogy 64 4. Tellurium distribution and ore deposits 65 5. Tellurium in the environment 66 6. Biogeochemistry of tellurium 67 7. A tellurium biogeochemical cycling model 68 Acknowledgements 69 Footnotes 70 References 71 1. INTRODUCTION

72 Tellurium (Te) was discovered in 1783 by Franz Joseph Müller von Reichenstein, but fully

73 publicised only over a decade later by Martin Heinrich Klaproth, who named the new element

74 after the Latin word for "earth", tellus (Emsley, 2011; Klaproth, 1798). With an estimated

75 crustal abundance of ~5 µg/kg (reported range 1 to 27 µg/kg; Emsley, 2011; Vaigankar et al.,

76 2018; Wedepohl, 1995), it is one of the least abundant elements in the lithosphere and

77 comparable to crustal abundances of precious metals gold (Au) and platinum (Pt) (Emsley,

78 2011). Recently, Te has come into prominence due to new industrial applications, including in

79 cadmium telluride (CdTe) solar panels (Diso et al., 2016; Goldfarb, 2014; Reese et al., 2018),

80 thermoelectric devices (Bae et al., 2016; Knockaert, 2011; Lin et al., 2016), batteries (Ding et

81 al., 2015; He et al., 2016; He et al., 2017), and nanomaterials like CdTe quantum dots (Mahdavi

82 et al., 2018). Furthermore, the recent nuclear incident at Fukushima led to severe contamination

83 by the radioisotope 132Te, renewing interest in the biogeochemical mechanisms involved in Te

84 transport in the environment (e.g. Gil-Díaz, 2019; Tagami et al., 2013).

85 Tellurium is distributed unevenly through the Earth’s crust. Hydrothermal and magmatic

86 processes are the key mechanisms leading to high Te concentrations and the formation of

87 primary Te minerals (Brugger et al., 2016). Tellurium is an essential element in over 170

88 minerals, making it the most anomalously diverse element in mineralogy, i.e. it forms the

89 greatest number of minerals relative to its crustal abundance (Christy, 2015; Pasero, 2019).

90 Tellurides are primary minerals containing reduced Te (formal oxidation state -II to 0; e.g.,

91 calaverite, krennerite, sylvanite; Figure 1a-c) and elemental tellurium (Figure 1d); secondary

92 minerals comprise tellurites (oxidation state +IV) and tellurates (+VI) (e.g., teineite, zemannite,

93 and jensenite, Figure 1d-f). The designations ‘primary’ and ‘secondary’ minerals relate to

94 formation conditions. Primary minerals form deeper in the crust under anoxic conditions from

95 hydrothermal fluids or silicate melts (Ciobanu et al., 2006; Zhang and Spry, 1994); whereas 96 secondary minerals form via weathering of primary minerals under the oxidising conditions of

97 near-surface environments (Christy et al., 2016a). Some tellurites and tellurates possess non-

98 linear optical properties (Norman, 2017; Weil, 2018; Yu et al., 2016) with potential

99 applications in the electronics industry. Nonetheless, most industrial applications for Te utilise

100 tellurides (Amatya and Ram, 2012; Woodhouse et al., 2013; Yeh et al., 2008).

101 In 2010, the US Department of Energy classified Te as a critical metal with an anticipated

102 global supply shortfall by 2025 (Bauer et al., 2010), and Te remains on the list of critical metals

103 published by the US Department of the Interior in 2018 (USDOI, 2018). The global Te industry

104 is still in its infancy with a global production of 440 metric tonnes and estimated reserves of

105 31,000 metric tonnes from Te contained in copper ores (Anderson, 2019). Currently, >90% of

106 Te (along with Se) is recovered from copper anode slimes as a by-product of the electrolytic

107 refining of copper (Kyle et al., 2011; Makuei and Senanayake, 2018), and Te supply is thus

108 intrinsically linked to the Cu mining industry. Recent advances in industrial uses of Te focus

109 on CdTe solar panels, which currently supply five percent of the global solar panel market

110 (USDOE, 2019). Due to a growing world population and concurrent attempts to limit man-

111 made climate change, renewable energy industries including CdTe solar panels are growing in

112 prominence (see Figure 2; Frishberg, 2017; Nuss, 2019; Wang, 2011).

113 The increased demand for Te will inevitably result in increasing Te contamination around

114 mining and industrial sites (e.g. Kagami et al., 2012), and the decommissioning of CdTe solar

115 panels also has the potential to be a source of contamination, in particular to

116 groundwater (Fthenakis and Wang, 2006; Marwede and Reller, 2012; Ramos-Ruiz et al., 2017b;

117 Xu et al., 2018). Another short-term anthropogenic source of Te contamination are the

118 radiogenic isotopes 132Te and 129mTe released to the environment in nuclear spills or explosions.

119 This comprises both nuclear weapons testing (particularly from the 1940s to the 1970s) and

120 accidental spillage from power plant failure such as the Chernobyl and Fukushima Daiichi 121 nuclear disasters (Dickson and Glowa, 2019; Yoschenko et al., 2018). The radioactive and

122 biologically active decay product of 132Te, 132I, is of most concern, and a greater understanding

123 of Te biogeochemical cycling could have provided better and longer-lasting solutions for

124 cleaning up radioactive materials following the Fukushima spill (Gil-Díaz, 2019).

125 Research in Te biogeochemistry continues to be of scientific interest because the cycling of

126 this element in near-surface environments is dynamic, as the transformation of Te oxidative

127 states can form both inorganic and organic compounds (Belzile and Chen, 2015; Bonificio and

128 Clarke, 2014; Chasteen et al., 2009). In terms of biogeochemical processes at the cellular level,

129 mechanisms for detoxifying often involve reduction of soluble Te oxyanions (i.e., tellurite and

130 tellurate anions) (Piacenza et al., 2017; Taylor, 1996; Taylor, 1999). These soluble Te

131 oxyanions are toxic to some microorganisms at low concentrations, i.e., 1 mg/L or an

132 equivalent 4 µM (Presentato et al., 2019), which are orders of magnitude less than known

133 cytotoxic concentrations of mercury or cadmium (Chasteen et al., 2009; Presentato et al., 2016).

134 As such, Te solubility is a key factor contributing to its toxicity; reduced Te compounds (e.g.,

135 metallic Te) have low solubility and are therefore considered less toxic as they are not easily

136 bioavailable. Reduction of Te oxyanions by microorganisms follows two major pathways,

137 which may be either active or passive: bioprecipitation and, to a lesser extent,

138 biovolatilisation (Chasteen and Bentley, 2003). Active bioprecipitation (also known as

139 biomineralisation) results in the formation of nanoparticles of elemental Te, and

140 biovolatilisation in the formation of volatile, organic forms of Te such as dimethyl telluride. In

141 terms of passive bioprecipitation/biomineralisation, microorganisms as well as other organic

142 material, e.g., extracellular polymeric substances (EPS), can act as a sorbent material as well

143 as a reductant for Te oxyanions. As such, the accumulation of reduced Te can occur over time

144 as long as Te oxyanions are supplied to the system and a consistent presence of biomass is

145 available to serve as a sorbent material and reductant (Tanaka et al., 2010). Biooxidation of Te 146 leading to its solubility (and intuitively, its mobility in the environment) is the less-studied

147 process of biogeochemical cycling relative to Te oxyanion reduction. Metal-tolerant

148 microorganisms are capable of indirectly oxidising tellurides by producing an oxidant (e.g. Fe-

149 oxidisers producing Fe3+) as a by-product of their metabolism (Climo et al., 2000b).

150 Collectively, the summation of reduction and oxidative processes contribute to the

151 biogeochemical cycle of Te under near-surface environmental conditions and provide both

152 organic and inorganic pathways for precipitation, sorption and oxidation (Filella et al., 2019).

153 Here we focus on the environmental (bio)geochemistry of Te, by first tying together existing

154 research in mineralogy, geochemistry and microbiology – each discipline extensively studied

155 in their own right, but not often explicitly linked. Over the past decade, various aspects of the

156 biosphere and lithosphere have been shown to influence the dissolution, re-precipitation and

157 mobility of Se, the chalcogen element located above Te in the Periodic Table (Bailey, 2017;

158 Nancharaiah and Lens, 2015; Sharma et al., 2015; Tan et al., 2016; Ullah et al., 2018). In

159 addition, precious metals such as Au (Reith et al., 2013; Sanyal et al., 2019; Southam et al.,

160 2009) and Pt (Reith et al., 2014; 2016; 2019), which have had been generally considered to be

161 inert, have been show to display complexing biogeochemical cycling. To our knowledge, an

162 interdisciplinary research perspective of Te cycling is still lacking in the literature; therefore,

163 here we develop a model for a global biogeochemical cycling of Te in near-surface

164 environments. This Te biogeochemical cycling model helps to identify gaps in our current

165 understanding of Te biogeochemistry, and allows critical evaluation of various environmental

166 factors contributing to Te mobility, which is becoming increasingly important as anthropogenic

167 activity associated with Te applications is a greater factor in environmental contamination. 168 2. PHYSICAL AND CHEMICAL PROPERTIES OF TELLURIUM

169 Tellurium has the atomic number 52 and belongs to the chalcogen group on the periodic table,

170 below oxygen (O), sulphur (S; Kagoshima et al., 2015), and selenium (Se; Ullah et al., 2018),

171 and above radioactive polonium (Po; Ram et al., 2019; see Supplementary Table 1). Tellurium

172 has 39 known isotopes, eight of which are naturally occurring. Half of those isotopes, 122Te

173 (natural abundance 2.5%), 124Te (4.6%), 125Te (6.9%), and 126Te (18.7%), are stable. The other

174 four naturally occurring isotopes are unstable, i.e., 120Te (0.09%), 123Te (0.87%), 128Te (31.8%)

175 and 130Te (34.5%), but with long to extremely long half-lives of ~1016, 9.2 × 1016, 2.2 × 1024

176 (the longest known half-life of any isotope) and 7.9 × 1020 years, respectively (Emsley, 2011).

177 Interestingly, the long-lived radioactive isotopes of Te are more abundant than the stable

178 isotopes by a ratio of ca. 2:1. A ninth isotope, 132Te (half-life 3.204 days), is of considerable

179 concern as a nuclear waste product and was the third most abundant element released by the

180 Fukushima Daiichi nuclear disaster (Endo et al., 2018). Almost all 132Te (aside from trace levels

181 found in U ores from natural nuclear fission events; Emsley, 2011) has been produced

182 anthropogenically. Additionally, 129mTe (‘m’ indicating a metastable isotope with the nucleus

183 in a long-lived excited state; 129mTe decays via gamma radiation to 129Te with a half-life 33.6

184 days) is also produced in nuclear waste and spills (Watanabe et al., 2012; Endo et al., 2018),

185 and some other radioactive isotopes like 119mTe (half-life 4.70 days) are generated synthetically

186 as precursors for medical uses (Bennett et al., 2019).

187 Of the chalcogens, Te has the highest melting and boiling points, at 449.5 and 988 °C,

188 respectively. However, in polymetallic systems, Te is one of the “low-melting point chalcophile

189 metals” together with Ag, As, Au, Bi, Hg, Sb, Se, Sn, and Tl, forming melts at metamorphic

190 and hydrothermal temperatures between 500 and 600 °C, depending on pressure (Frost et al.,

191 2002; Tooth et al., 2011). Elemental Te is a semiconductor that is also photoconductive

192 (increased conductance when exposed to light, Liu et al., 2010)), although Te is more 193 commonly combined with other elements in semiconducting applications (Marwede and Reller,

194 2012).

195 In terms of its aqueous chemistry, Te is similar to Se, sharing fewer parallels with S and Po,

196 but previous studies on Te have shown the danger of assuming that it behaves analogous to

197 other chalcogens (Chivers and Laitinen, 2015). Like S and Se, Te occurs in four main formal

198 oxidation states in aqueous solution: -II, +II (least stable and not known naturally), +IV and

199 +VI. The +IV and +VI may coexist in the same solution due to slow reaction kinetics of

200 aqueous Te oxidation and reduction (Filella and May, 2019). Reduced Te compounds (formal

201 oxidation state -II and elemental Te) are typically poorly soluble; for example, the solubility

202 product (log Ksp; reaction 2.1) for silver telluride (hessite) is -71.7 (Chen et al., 2002):

203 Ag Te( ) 2Ag ( ) + Te ( ), = [Ag ] [Te ] (2.1) + 2− + 2 2− 2 𝑠𝑠 ↔ 𝑎𝑎𝑎𝑎 𝑎𝑎𝑎𝑎 𝐾𝐾sp 204 Nonetheless, cadmium telluride, bismuth telluride and elemental Te were shown to be

205 sparingly soluble in ambient conditions by Bonificio and Clarke (2014), diffusing across an

206 agar plate by a poorly understood mechanism.

207 The simplest Te anion is telluride (Te2-). Unsurprisingly, the Te2- anion (2.21 Å) has a larger

208 radius than the selenide (Se2-, 1.98 Å) and sulphide (S2-, 1.84 Å) anions. The difference in radii

209 is 11% for Se2- but 20% for S2-, exceeding the 15% limit of the Goldschmidt rule, and meaning

210 that Te2- substitution for S2- involves significant structural strain (Blundy and Wood, 1994;

211 Shannon and Prewitt, 1969); yet sulphide minerals commonly can incorporate mg/kg levels of

212 Te (see Table 2). Additionally, as is the case for other p block elements, the hydride (hydrogen

213 telluride, H2Te(g)) is volatile (Cooke and McPhail, 2001; Grundler et al., 2013), although,

2+ 214 unlike Se, Te does not readily form a volatile chloride (Te Cl2) when heated to 200°C in the

215 presence of HCl with pH below 0 (Chen et al., 2016). Tellurium atoms often polymerise to

216 form more complex polytelluride anions with formal oxidation states between -II and 0; the 2- 217 simplest aqueous polytelluride ion is the linear Te2 ditelluride ion (Brugger et al., 2012; Ruck

218 and Locherer, 2015; Singh and Sharma, 2000). In minerals, Te participates in varied forms of

219 intermetallic bonding in tellurides (Bindi and Biagioni, 2018; Helmy et al., 2007; Moëlo et al.,

220 2008), for instance forming Te–Ag bonds in hessite; and Te–Au and Te–Te bonds in calaverite

221 (Figure 3). Te–Te bonds have metallic character, and metal–Te bonds tend to have strong

222 covalent character due to the small difference in Pauling electronegativity between Te (2.1)

223 and many metals such as Cu (1.90), Ag (1.93) and Pt (2.28). The non-metal O, by comparison,

224 has a higher electronegativity of 3.44, allowing Te4+ and Te6+ to form ionic bonds to O

225 (Figure 3). Geometric arrangements of Te4+–O or Te6+–O bonds around a Tem+ centre form

m+ m-2n 226 [Te On] oxyanions (Christy et al., 2016a). Tellurium (IV) has a stereochemically active

227 lone electron pair, and as a result forms a variety of distorted (hemidirected) coordination

4+ 2- 4+ 4- 4+ 6- 228 polyhedra (Christy and Mills, 2013), e.g., [Te O3] , [Te O4] and [Te O5] ; sometimes

229 there is more than one coordination in the same structure (Missen et al., 2019). In contrast, Te6+

6+ 230 lacks a lone electron pair, and occurs exclusively in minerals as Te O6 octahedra (Christy et

231 al., 2016a; Mills and Christy, 2013) (Figure 3). The structural diversity of Te–O compounds is

232 further discussed in the following section.

233 3. TELLURIUM MINERALOGY

234 As a chalcophile element (Christy, 2018), Te typically occurs sulphide ore deposits with other

235 chalcophile elements such as Ag, Cu and Pb (see Table 2). Rather than forming separate

236 telluride minerals, which tend to be minor phases in most deposits, the bulk of the primary Te

237 is typically found associated with sulphides, i.e., Te substitutes for S in common sulphide

238 minerals such as chalcopyrite, covellite, galena, pyrite, pyrrhotite and sphalerite (Brugger et

239 al., 2016; Dill, 2010; Hattori et al., 2002; Simon and Essene, 1996; Vikentyev, 2006). Pyrite is

240 the most studied host sulphide for Te (Cook et al., 2009a; Deditius et al., 2010, 2014; 241 Dmitrijeva et al., 2020; Keith et al., 2018; King et al., 2014). The mechanisms of Te

242 incorporation in pyrite are complex and dynamic, involving for example the preferential

243 incorporation of Te on the (1 1 0) pyrite surface (Chouinard et al., 2005).

244 Tellurium minerals form in a variety of geological environments (see Section 4.2). As

245 previously discussed, Te mineralogy is the most ‘anomalously diverse’ of all elements despite

246 its low crustal abundance (Christy, 2015). As of 2019, the International Mineralogical

247 Association (IMA) recognises more than 175 Te minerals (Pasero, 2019), with several more

248 valid but unnamed Te mineral species also known (Smith and Nickel, 2007). These minerals

249 may be divided into almost equal numbers of primary (oxidation states almost entirely#1 -II to

250 0) and secondary (oxidation states +IV and +VI) minerals, although more new secondary

251 minerals have been described in the past decade (Kampf et al., 2016). Important Te minerals

252 are listed in Table 1, and a current list is provided in Supplementary Table 2.

253 Primary minerals form the bulk of Te minerals by weight/natural abundance. Tellurium has a

254 close affinity to Au and Ag, making Au and/or Ag tellurides the most important primary Te

255 minerals (See also Table 1). Tellurium is one of the few elements with which Au forms

256 minerals. Fourteen Au–Te minerals are currently known, the most common being calaverite

257 (AuTe2, Figure 1a), krennerite (Au3AgTe8, Figure 1b), sylvanite [(Au,Ag)2Te4, Figure 1c] and

258 petzite (Ag3AuTe2). Twenty-two primary Ag–Te minerals are known, the most common of

259 which is hessite, Ag2Te. Elemental Te is also a primary mineral in some Te-rich deposits

260 (Figure 1d). There are 36 Bi–Te minerals (29 primary and 7 secondary minerals)#2. Primary

261 Bi–Te minerals can be abundant in some deposits (Ciobanu et al., 2009), for example

262 tetradymite (Bi2Te2S) is the main Te ore mineral in the Dashuigou deposit, China (Mao et al.,

263 2002). Only a handful of telluride minerals have reliable thermodynamic data describing their

264 formation, including calaverite (Mills, 1974) and more recently, two Pt telluride minerals

265 (Olivotos and Economou-Eliopoulos, 2016). 266 Secondary Te minerals develop in the topmost reaches of deposits, where primary minerals

267 come into contact with oxygenated groundwaters (Dill, 2010; Williams, 1990). Although

268 secondary minerals of some elements are prevalent enough to form economic deposits (e.g.,

269 non-sulphide Zn deposits; Boni et al., 2003; Hitzman et al., 2003), secondary Te minerals are

270 rare and occur only in sub-economic amounts – often less than a gram of such minerals are

271 estimated to occur worldwide. Additionally, obtaining thermodynamic data for these minerals

272 is near impossible because of the difficulty in obtaining sufficient amounts of pure material;

273 synthesis usually leads to fine-grained mixtures.

4+ 4+ 274 Figure 4 shows the structural diversity of Te –O minerals, including isolated Te On

4+ 275 polyhedra, and Te On polyhedra linked in non-cyclic finite units, infinite chains, infinite layers

276 and infinite frameworks. This diversity explains the large amount of tellurite minerals, and is

277 due to the flexible and asymmetric coordination environment of the Te4+ ion, which results

278 from its lone electron pair (Christy and Mills, 2013). Similar structural diversity, from units to

6+ 6+ 279 frameworks, is possible for Te –O minerals, although most tellurate minerals contain Te O6

280 octahedra isolated from each other, with much of the structural diversity driven by the varied

281 crystal chemistry of associated cations like Cu2+ (Christy et al., 2016b). Purely cyclic finite

4+ 6+ 282 units of TeOn polyhedra (neither Te nor Te ) are not yet known in any Te minerals (Christy

283 et al., 2016a).

284 4. TELLURIUM DISTRIBUTION AND ORE DEPOSITS

285 4.1 Overview of tellurium distribution in the Earth’s crust

286 Tellurium is much more abundant in the solar system – 2.28-2.32 mg/kg Te based on C1

287 chondrite (Anders and Grevesse, 1989; Lodders, 2010) – than in the Earth’s crust (5 µg/kg).

288 The low crustal abundance of Te results from three processes active during the Earth’s

289 formative years. First, the Earth formed from Te- and other volatile-depleted chondritic 290 meteorites (Braukmüller et al., 2019). Second, volatile Te compounds such as hydrogen

291 telluride (H2Te) formed and were subsequently lost to outer space during accretion (O'Neill

292 and Palme, 2008). Finally, Te acts as a siderophile under highly reducing conditions, resulting

293 in its sequestration with metallic iron and nickel in the Earth’s core (Rose-Weston et al., 2009;

294 Wang and Becker, 2013). Hence, most Te in the crust is thought to have been added in a ‘late

295 veneer’ (Wang and Becker, 2013), which over geologic timescales has differentiated into the

296 characteristic uneven distribution of Te known today.

297 The mobility of Te from the mantle to the atmosphere can be grouped according to the physical,

298 geochemical and biochemical processes that dominate the given environment (Figure 5).

299 Major sinks for Te include mineable or accessible mineral deposits, weathered rocks, soils, and

300 sediments, with the processes governing the interplay between these sinks further discussed in

301 Section 7.1. As discussed in Section 3, Te forms over 175 minerals, chiefly in and around

302 economic deposits (see Section 4.2 and Figure 5). Tellurium tends to be enriched in soils (up

303 to ~50 µg/kg, locally higher near Te deposits), from where it may be solubilised and enter an

304 aqueous environment (Figure 5). However, Te is highly depleted in seawater (<2 ng/L) and

305 surface freshwater (<20 ng/L) compared to its crustal abundance (Table 3) (Belzile and Chen,

306 2015; Emsley, 2011; Gil-Díaz et al., 2019a; Wedepohl, 1995); this is due to the strong sorption

307 of Te(IV/VI) oxyanions onto mineral surfaces (see Section 5.2) (Qin et al., 2017). Tellurium is

308 generally below the level of ng/m3 in airborne particulates (Belzile and Chen, 2015), locally

309 higher near Te-rich areas due to release of volatiles.

310 Among sediments, Te levels have an average value around 35 µg/kg (see Figure 5), although

311 Te is particularly enriched in ferromanganese nodules on the ocean floor (Baturin, 2012).

312 Conservative estimates suggest average enrichment on the order of 1 mg/kg, i.e. three orders

313 of magnitude higher than the average crustal concentration, with some nodules containing over

314 200 mg/kg (Figure 5; Baturin, 2012; Hein et al., 2003), from where the nodules may be 315 subducted back into the Te-rich mantle. Elevated levels of Te are also found in sedimentary

316 red beds and black shales. Reduction spheroids in red beds (British Isles Triassic, Parnell et al.,

317 2016; worldwide Mesoproterozoic, Parnell et al., 2018) commonly display average enrichment

318 to 1-10 mg/kg, and often contain micron-scale grains of telluride minerals. Tellurium levels in

319 Neoproterozoic black shales from the Gwna Group in the British Isles display enrichment up

320 to 30 mg/kg via similar processes which occur in ferromanganese nodules (Armstrong et al.,

321 2018).

322 Volcanoes are another source of environmental Te, where volatile forms of Te (e.g., H2Te(g))

323 are released through eruptions, quiescent degassing (e.g., fumaroles), or hydrothermal activity.

324 For example, Te occurs at 10-1000 mg/kg levels in volcanogenic sulphur (see Figure 5; Yu et

325 al., 2019). The high temperature (~600 ˚C) fumaroles at the Avacha Volcano, Kamchatka,

326 Russia, contain up to 15.9 mg/kg Te (Okrugin et al., 2017) (Table 3), and native Te has been

327 identified in fumarolitic deposits from Vulcano, Italy (Fulignati and Sbrana, 1998). Deep-sea

328 black-smoker massive-sulphide and volcanogenic-sulphur deposits typically contain Te

329 enriched by four orders of magnitude compared to average crustal levels (Butler and Nesbitt,

330 1999; De Ronde et al., 2015; Greenland and Aruscavage, 1986; Yu et al., 2019).

331 Tellurium is also enriched in organic-rich rocks and coals (Belzile and Chen, 2015), with

332 concentrations up to 2 mg/kg in the pyritic coals of Brora, Scotland (Bullock et al., 2017).

333 Tellurium stored in coal is subsequently released into the atmosphere through the burning of

334 coal to produce electricity (see Figure 5). There are relatively few studies on the Te content of

335 crude oil and natural gas. Green (2011) calculated that 4 to 220 tonnes of Te were processed

336 during crude oil refinement in 2010, and <100 tonnes of Te processed during natural gas

337 refinement, though the average amounts in each source are likely to be <1 mg/kg. Parnell et al.

338 (2015) used pyrite Te levels as a proxy for Te content of natural oil reservoirs. The average Te 339 content of pyrite associated with biodegraded palaeo-oil reservoirs is in the 100s of µg/kg, as

340 opposed to less than 30 µg/kg for other pyrites in central England (Parnell et al., 2015).

341 4.2 Tellurium ore deposits

342 4.2.1 Overview

343 Tellurium is produced from only a handful of localities, and no deposit is currently mined

344 solely for Te. For instance, Te is recovered as a by-product of Au mining from the Kankberg

345 mine in Sweden (Goldfarb, 2014; Goldfarb et al., 2017), which has local epithermal-like

346 mineralisation in a volcanogenic massive sulphide district; and together with Au from the

347 epithermal vein deposits of Dashuigou and Majiagou in the Sichuan and Shaanxi provinces of

348 China (Mao et al., 2002). Additionally, the company Deer Horn Capital expects to begin

349 production of Te together with Au and Ag from the Deer Horn area of British Columbia,

350 Canada. The average Te grade at Deer Horn is 118 mg/kg Te, with an expected total amount

351 of 67 tonnes recoverable (Meintjes et al., 2018). Other major producers of Te are the United

352 States, Canada, Peru and Japan (Anderson, 2019; Emsley, 2011). Although it is rarely

353 recovered, Te is enriched (100’s of µg/g to wt.%) in many base- and precious-metal deposits.

354 The largest reserves based on the amounts of Te produced by Cu mining are in China

355 (6,600 metric tons), Peru (3,600 metric tons) and the United States (3,500 metric tons)

356 (Anderson, 2019). Nonetheless, the disconnect between relatively large Te reserves (even more

357 so if Te sources in their own right were included) and the relatively small amounts actually

358 produced means that Te is classified as a critical mineral commodity (USDOI, 2018).

359 The most important deposit types are of magmatic and hydrothermal origin. Note that in this

360 and the following sections, the deposits listed here are the most Te-rich, or where Te is an

361 important constituent of the economic mineral assemblage. Many other mines and deposits

362 have reported telluride occurrences, but these may be rare or even singular occurrences of 363 minerals. Other deposits have no reports, as Te was often unanalysed, though usually in current

364 exploration Te is included in standard analysis regimes.

365 Tellurium enrichment commonly occurs in association with Au and sometimes Ag in many

366 (usually hydrothermal) ore deposits, and with Platinum Group Minerals (PGMs) in a smaller

367 number of deposits (usually magmatic, e.g. Ciobanu et al., 2006; Keith et al., 2018; Pals et al.,

368 2003). Several magmatic Copper–Nickel–Platinum-Group-Metal (Cu–Ni–PGM) sulphide

369 deposits (e.g. Noril’sk (Genkin and Evstigneeva, 1986) and Kola Peninsula (Subbotin et al.,

370 2019), in Russia; Bushveld, in South Africa (Kingston, 1966); and Sudbury, in Canada (Dare

371 et al., 2014)) are enriched in Te (e.g., up to 150 mg/kg in chalcopyrite-rich massive sulphide

372 ores from Sudbury; Dare et al., 2014). The major sulphide minerals in Cu–Ni–PGM deposits

373 are pyrrhotite, pentlandite and chalcopyrite, which may host Te themselves (Table 2), although

374 Te-rich Cu–Ni–PGM deposits tend to contain small amounts of tellurides (Holwell et al., 2017).

375 Even though Cu–Ni–PGM sulphide deposits are the only non-hydrothermal Te deposit type,

376 they are some of the larger Te reserves.

377 Outside of magmatic deposits, the majority of Te deposits are hydrothermal in nature,

378 encompassing the following deposit types (Goldfarb et al., 2017):

379 • Epithermal deposits (e.g. Cripple Creek, Colorado, USA (Kelley et al., 1998;

380 Thompson et al., 1985) and Emperor, Fiji (Pals and Spry, 2003; Pals et al., 2003),

381 localities 49 and 4 on Figure 6).

382 • Orogenic gold deposits (e.g. Sunrise Dam, Australia (Sung et al., 2009; Sung et al.,

383 2007) and Ashanti, Ghana (Bowell, 1992), localities 78 and 13 on Figure 6).

384 • Volcanogenic Massive Sulphide (VMS) deposits (e.g. Ural Mountains, Russia

385 (Vikentyev, 2006) is by far the best described, locality 28 on Figure 6). 386 • Iron Oxide-Copper-Gold (IOCG) deposits (e.g. Olympic Dam, Australia (Rollog et al.,

387 2019), locality 1 on Figure 6).

388 • Porphyry deposits (e.g. Almalyk, Uzbekistan (Cheng et al., 2018) and Mount Milligan,

389 British Columbia, Canada (LeFort et al., 2011), localities 19 and 74 on Figure 6).

390 • Intrusion-related Au deposits (e.g. Dongping Au-Te field in Hebei, China (Sillitoe and

391 Thompson, 1998) and Bjorkdal, Sweden (Roberts et al., 2006), localities 79 and 81 on

392 Figure 6).

393 • Skarn deposits (e.g. Ortosa, Spain (Cepedal et al., 2006) and Geodo, South Korea (Kim

394 et al., 2012b), localities 49 and 16A on Figure 6).

395 • Carlin-type gold deposits (e.g. Deep Star, Nevada, USA (Fleet and Mumin, 1997; Heitt

396 et al., 2003) and Zarshuran, Iran (Asadi et al., 2000; Mehrabi et al., 1999), localities 69

397 and 31 on Figure 6).

398 As the majority of Te deposits are hydrothermal, and indeed hydrothermal processes are key

399 to determining the modern surface distribution of Te, the hydrothermal geochemistry of

400 tellurium is discussed in the following section.

401 4.2.2 Hydrothermal geochemistry of tellurium

402 In contrast to surface waters, hydrothermal fluids can be enriched in Te, although few data are

403 currently available. Waters from modern geothermal systems routinely carry Te at the µg/L

404 level (seawater <2 ng/L), and fluid-inclusions from Te-rich epithermal and porphyry systems

405 may carry as much as 100’s of mg/L Te (Table 3). Tellurium transport in hydrothermal fluids

406 remains “incompletely understood” (Goldfarb et al., 2017) due to the paucity of experimental

407 data at elevated temperatures. The seminal work of McPhail (1995) still provides the most

408 extensive review of Te thermodynamic data at room temperature, as well as isocoulombic

409 extrapolations, allowing prediction of Te transport and deposition in waters and vapours to 410 350˚C. Experimental studies by Brugger et al. (2012), Grundler et al. (2013) and Etschmann et

411 al. (2016) provide the only direct evidence of the nature and geometry of Te complexes at

412 elevated temperatures, as well as updated thermodynamic properties for a number of key

413 complexes. Thermodynamic calculations based on these properties have shown that Au and Te

414 tend to have higher solubility in basic fluids (Brugger et al., 2012), meaning that alkaline and

415 silica-undersaturated host rocks support more efficient transport and enrichment of Te and Au

416 (Smith et al., 2017).

417 Tellurium is generally extremely poorly soluble under reducing conditions, in the form of

2- - 2- 418 tellurides (e.g., Te and HTe ) and polytelluride (e.g., Te2 ) complexes (Figure 7). Brugger et

419 al. (2012) showed that polytelluride species are stable to high temperatures (599 °C; 800 bar),

420 and are thus expected to be an important form of Te in basic fluids at high temperatures (e.g.,

421 CO2-rich fluids) (Cook et al., 2009c; Cooke and McPhail, 2001; Gao et al., 2017; Grundler et

422 al., 2013; Keith et al., 2018). Brugger et al. (2012) also showed that branched polytelluride

2- 423 species are stable at low temperature, but only the Te2 dimer remains at high temperature.

- 2- 424 Under more oxidising conditions, the tellurite complexes H2TeO3(aq), HTeO3 , and TeO3

425 become increasingly stable as temperature increases (Figure 7). At 300˚C, they are stable close

426 to the hematite/magnetite buffer (Figure 7), leading Grundler et al. (2013) to propose that these

427 complexes account for Te transport in some Te-rich systems (e.g., porphyry-epithermal

428 systems). In situ XAS measurements by Grundler et al. (2013) showed that these tellurite

429 complexes share a trigonal pyramidal [TeO3] geometry (with Te at the apex and the three O

430 atoms at the vertices), and the electron lone pair above the pyramid. The one-sided geometry

431 of Te4+ complexes plays a key role in their interaction with other species. In contrast to S and

432 Se, Te can form complexes with halides (metal-like behaviour). Etschmann et al. (2016)

433 showed that the square pyramidal [TeCl4(aq)] complex occurs in very acidic brines, but this

434 complex is likely to play a minor role in natural environments. Figure 7 also illustrates that 435 tellurate complexes [typically octahedral, e.g. H6TeO6(aq)] exist only at low temperature in the

436 presence of significant amounts of molecular oxygen, and hence are important only in (near)-

437 surface environments.

438 An important aspect of the hydrothermal geochemistry of Te is the fact that Te partitions

439 strongly into the vapour phase upon separation under reducing conditions in the form of

440 H2Te(g), leading to relative enrichment of Te in the vapour phase. These volatile phases are

441 believed to play an important role in the formation of “bonanza” Au–Te ores in epithermal

442 systems (Cook et al., 2009c; Cooke and McPhail, 2001; Gao et al., 2017; Grundler et al., 2013;

443 Keith et al., 2018).

444 Finally, as a “low-melting point chalcophile metal”, Te will also be enriched together with Ag,

445 As, Au, Bi, Hg, Sb, Se, Sn, and Tl in melts at temperatures between 500 and 600 °C (Frost et

446 al., 2002; Tooth et al., 2011). These melts can play a key role in Te enrichment, either via

447 physical migration (Tomkins et al., 2006), via interaction with hydrothermal fluids (McFall et

448 al., 2018; Tooth et al., 2008; 2011), or with magmatic vapours (Okrugin et al., 2017; Yu et al.,

449 2019). These processes thus play a key role in enriching Te together with Au and Ag during

450 the ore-forming process.

451 4.2.3 Distribution of Te deposits

452 Figure 6 shows the worldwide distribution Te deposits with respect to the underlying crustal

453 provinces. Localities in the Figure are itemised in Supplementary Table 3. The majority of Te

454 deposits occur in Phanerozoic Orogenic belts, which reflects the predominance of epithermal

455 and porphyry-type deposits, the role of subduction in the formation of these deposits, and the

456 destruction of these shallow deposits by erosion in older terrains (Kesler and Wilkinson, 2008).

457 This relation is particularly noticeable on the western side of North America and through the

458 central Orogen provinces of Eurasia. Links between magmatic Cu–Ni–PGM deposits and 459 porphyry or epithermal Cu–Au(–Te) deposits have recently been determined, with Te a useful

460 tracer of the metallogenic continuum between these deposit types (Holwell et al., 2019).

461 Epithermal Au and Te deposits are some of the largest and highest grade Te resources;

462 examples include Moctezuma mines, Mexico (Deen and Atkinson Jr, 1988), Cripple Creek,

463 Colorado (Kelley et al., 1998), Emperor, Fiji (Pals and Spry, 2003) and Săcărâmb, Romania

464 (Ciobanu et al., 2004). Epithermal deposits are typically associated with alkaline volcanic rocks,

465 and although limited in their spatial distribution, they are economically important (du Bray,

466 2017). Tellurium-rich epithermal deposits typically contain abundant tellurides that usually

467 contain a large proportion of the precious metals Au and Ag, as well as heavy metals such as

468 Pb (e.g., altaite), Bi (e.g., tetradymite) and Hg (e.g., coloradoite) (Dill, 2010). Telluride

469 minerals typically form late in the paragenesis, after the bulk of associated S has been removed

470 from solution to form sulphide minerals (Watterson et al., 1977).

471 Porphyry Cu–Au–Te deposits are mainly found in western North America in the Orogenic or

472 Extended Crust provinces, and include famous localities like Bingham Canyon, Utah and the

473 world-class but not yet producing Pebble deposit in remote western Alaska.

474 Although many orogenic gold deposits contain minor amounts of telluride minerals, a few have

475 significant amounts of Au bound to Te; these include California’s most famous gold-rush

476 deposits in the Mother Lode region, and the Sunrise Dam deposit in Western Australia (Sung

477 et al., 2009; Sung et al., 2007). Note that the genesis of the Te-rich mineralisation in some

478 orogenic Au deposits remains controversial; the most famous example is the giant Golden Mile

479 deposit, Western Australia (Bateman and Hagemann, 2004; Shackleton et al., 2003), in which

480 the Te-rich ores have been attributed to an epithermal-like genesis (Clout et al., 1990), but more

481 recently have been linked to higher temperature (400˚C) deep magmatic-derived fluids

482 (Mueller et al., 2019). 483 Tellurium-rich skarn deposits are rare and feature only a handful of examples, spread across

484 several continents, from Geodo in South Korea (Kim et al., 2012b) to Hedley in British

485 Columbia, Canada (Ray et al., 1987). Gold tends to be the main commodity in Te-bearing

486 skarns, with lower levels of Te associated with skarn Au deposits than in other deposit types.

487 Volcanogenic massive sulphide (VMS) deposits only comprise a handful of Te-rich examples,

488 including the Central Asian Au mines of Almalyk, Uzbekistan (Cheng et al., 2018) and Zod,

489 Armenia (Konstantinov and Grushin, 1970), with the Te associated with the sulphide minerals.

490 Kankberg, Sweden produces around 10% of the world’s Te as a by-product of Au processing

491 and occurs in a VMS region, but the local mineralisation at Kankberg itself is more epithermal

492 (Goldfarb et al., 2017).

493 A handful of Carlin-type and intrusion-type Au deposits also contain small amounts of Te.

494 Aside from a cluster of three Carlin-type deposits in Nevada (Getchell, Meikle and Deep Star),

495 which contain up to a maximum of 200 mg/kg Te in the ores, the only other Carlin deposit with

496 significant Te is the Zarshuran deposit in Iran (Asadi et al., 2000).

497 Perhaps the most unusual Te deposit is the IOCG deposit of Olympic Dam, Australia – one of

498 the world’s largest IOCG deposits. Other IOCG deposits may also contain Te, but in lesser

499 amounts. The Olympic Dam deposit is large enough that it contains enormous amounts of many

500 metals (Ehrig et al., 2012), and the average Te ore concentration is 2.5 mg/kg (Ehrig et al.,

501 2012; Rollog et al., 2019).

502 Magmatic deposits commonly occur in Shield and Platform geologic provinces, which

503 encompass areas with relatively flatter terrain than the Orogenic provinces. Montana’s

504 Stillwater complex is the only exception, being located in the Rocky Mountains on the

505 boundary of the Orogenic and Large Igneous provinces. Te whole rock grades at the Stillwater 506 complex are relatively low, not exceeding 20 mg/kg (Zientek et al., 1990), but still exceeding

507 baseline Te levels by four orders of magnitude.

508 4.2.4 Tellurium as a tool in mineral exploration

509 The enrichment of Te in precious and base metal deposits, coupled with its occurrence in

510 distinctive zones around ore deposits, means that it may be used as a geochemical tracer in

511 mineral exploration. Watterson et al. (1977) showed that proximal haloes containing at least

512 100 µg/kg Te extend up to 10 km away from central orebodies in the United States, with

513 proximal concentrations in excess of 10 mg/kg. For instance, the Ely Au-Cu-Ag porphyry

514 deposit in Nevada also has a Te-containing halo, with an average of 100 mg/kg Te recorded in

515 the jasperoids, gossans, and highly altered sedimentary carbonates in the mineralised zone of

516 the district. The levels of Te actually increase toward the boundaries of the Ely deposit, which

517 in total encompasses around 40 km2 surface area and approximately 60 km3 of Te-enriched

518 rock (Gott and McCarthy, 1966; Watterson et al., 1977). However, overall it seems that the use

519 of Te in geochemical exploration is still limited, and the wide variety of Te dispersion processes

520 remain poorly constrained, limiting the potential usefulness of Te as an Au indicator (and to a

521 lesser extent as a Ag indicator, as is unusual to find Ag and Te together without Au).

522 5. TELLURIUM IN THE ENVIRONMENT

523 5.1 Tellurium in the oxidation zone of primary Te-rich ores

524 Surface aqueous geochemistry and secondary mineralogy are linked through thermodynamics.

525 Tellurium forms a wide range of aqueous species (Grundler et al., 2013), some of which are

526 poorly constrained thermodynamically (Filella and May, 2019), along with a raft of secondary

527 minerals, many of which have few known properties outside of basic chemical and structural

528 characterisation (Christy et al., 2016b). The preservation of secondary minerals in the oxidation

529 zone provides a window into the dissolution process, allowing us to see secondary minerals 530 that record processes and conditions when the original hypogene ore is at complete equilibrium

531 with atmospheric oxygen (Williams, 1990). Overall, an improved understanding of the

532 deportment of Te from exposed Te deposits will also provide a useful analogy for

533 anthropogenic Te-contamination (Filella et al., 2019).

534 The first step in generating secondary Te minerals is the release of aqueous Te oxyanions via

535 dealloying of tellurides and/or the oxidation of other primary Te-bearing minerals,

536 predominantly sulphides such as pyrite. Dealloying releases the components of primary

537 minerals to aqueous solution. Solubilised Te oxyanions may precipitate by reaction with other

3+ 2+ 2+ 2+ 2+ 538 solubilised cations of metals like Fe , Zn , Cu , UO2 and/or Pb (Christy et al., 2016b;

539 Figure 8A), and dealloying often leaves behind the precious (and less soluble) metals in native

540 form (Okrugin et al., 2014; Figure 8B-D).

541 Secondary minerals often surround primary minerals as coatings or halos (Figure 1d). The

542 exact formation conditions and crystallisation processes of individual secondary minerals are

543 not fully understood, although contributing factors include local chemical environment, pH and

544 redox potential (Christy et al., 2016b). A lack of thermodynamic data (due in part to the lack

545 of synthetic analogues) on Te minerals contributes to the difficulty in understanding their

546 geochemical formation conditions (Christy et al., 2016b; Filella and May, 2019). Upon deeper

547 weathering, as observed above the high-grade Bambolla vein at Moctezuma, Mexico, Te occurs

548 predominantly in association with Fe-(Mn)-oxy-hydroxides (Figure 9), presumably in sorbed

549 forms (Hayes and Ramos, 2019).

550 Several studies have addressed the weathering of tellurides under mild (mostly ≤ 220˚C)

551 hydrothermal conditions; under these conditions the reaction occurs over a time-scale of hours,

552 whereas at ambient conditions months to years are required (Tenailleau et al., 2006). Studied

553 minerals include calaverite, AuTe2 (Zhao et al., 2009; Equation 5.1); krennerite, Au3AgTe8 (Xu 554 et al., 2013; Equation 5.2); and sylvanite, (Au,Ag)2Te4 (Zhao et al., 2013; Equations 5.3,

555 showing dissolution of sylvanite, and 5.4 showing the coupled precipitation of calaverite-I).

556 The oxidation of these tellurides leads to the formation of “mustard gold” (Figure 8C,D)

557 through dissolution of the parent telluride, subsequent reprecipitation of gold (or gold-silver

558 alloy) and diffusion of the aqueous Te away from the reaction front in the solution (Altree-

559 Williams et al., 2015; Zhao et al., 2009; Figure 8B). Although to date these reactions have been

560 studied in abiotic conditions, in the weathering environment they may be microbially mediated.

561 AuTe ( ) + 2O ( ) + 2H O 2H TeO ( ) + Au( ) (5.1)

2 𝑠𝑠 2 𝑎𝑎𝑎𝑎 2 ↔ 2 3 𝑎𝑎𝑎𝑎 𝑠𝑠 562 Au . Ag . Te ( ) + 8.05O ( ) + 7.89H O + 0.23HCl( )

3 28 0 72 8 2 2 563 𝑠𝑠3.77Au . Ag𝑎𝑎𝑎𝑎. ( ) + 0.23AgCl( ) + 8H𝑎𝑎𝑎𝑎TeO ( ) (5.2)

↔ 0 87 0 13 𝑠𝑠 𝑠𝑠 2 3 𝑎𝑎𝑎𝑎 564 Au Ag Te ( ) + 4.5O ( ) + 2HCl( ) + 3H O

x 2−𝑥𝑥 4 2 2 565 𝑠𝑠 AuCl( 𝑎𝑎𝑎𝑎) + (2 )AgCl𝑎𝑎𝑎𝑎 ( ) + 4H TeO ( ) (5.3)

↔ 𝑥𝑥 𝑎𝑎𝑎𝑎 − 𝑥𝑥 𝑎𝑎𝑎𝑎 2 3 𝑎𝑎𝑎𝑎 566 (1 )AuCl( ) + AgCl( ) + (2 )H TeO ( )

2 3 567 − 𝑥𝑥 𝑎𝑎𝑎𝑎 (Au𝑥𝑥 Ag𝑎𝑎𝑎𝑎)Te ( −) +𝑥𝑥 HCl( )𝑎𝑎𝑎𝑎+ (1.5 )H O

1−𝑥𝑥 𝑥𝑥 2−𝑥𝑥 2 568 +↔(2.25 )O ( ) 𝑠𝑠 𝑎𝑎𝑎𝑎 − 𝑥𝑥 (5.4)

− 𝑥𝑥 2 𝑎𝑎𝑎𝑎 569 Some of the best-known secondary Te mineral localities are historic, relatively small

570 epithermal Au and/or Ag deposits or prospects that are also rich in Te, most notably the

571 Moctezuma mines, Sonora, Mexico (21 new Te minerals; Jacobson et al., 2018; see Figure 6,

572 locality 56) and the Otto Mountain mines (16 new exclusively Te–O minerals; Christy et al.,

573 2016b), California, United States; locality 59). The prevalence of these deposits and description

574 of many rare secondary minerals on the western side of North America is partly due to avid

575 mineral collector interest in the area, meaning that most potential Te mineral localities have

576 been extensively explored (Localities 49-71 in Figure 6). Many secondary Te minerals are 577 known from just one locality, indicating that highly specific conditions are required for the

578 formation of some of these phases (Christy et al., 2016a; Kampf et al., 2016).

579 Notably, despite the prevalence and diversity of secondary Te minerals in some localities,

580 others display little or no secondary Te mineralisation. For example, secondary Te minerals

581 are virtually unknown in Australia, despite a number of Te-rich deposits and occurrences (e.g.,

582 Kalgoorlie; Sunrise Dam). These deposits occur in old cratons, and have been subjected to

583 weathering since at least the Mesozoic. This suggests that climate, intensity of weathering, and

584 the metallic elements in the parent tellurides play an important role in controlling the

585 paragenesis of secondary Te minerals. Extreme, prolonged weathering results in the dispersion

586 of Te: deep weathering generates large amounts of Fe oxides, and these scavenge Te via

587 sorption, limiting Te solubility and precipitation of secondary Te minerals (Hayes and Ramos,

588 2019; Figure 9). In young (<~10 My) deposits, weathering is limited, and although some

589 secondary Te minerals do form, for example at the Late Miocene (6.9–7.1 My) Aginskoe

590 deposit, Kamchatka, Russia (Andreeva et al., 2013; Takahashi et al., 2013; Figure 8), the extent

591 of the secondary Te mineral occurrence is highly limited (Okrugin et al., 2014). Mills and

592 Christy (2019) dated the secondary U-tellurite minerals schmitterite and moctezumite from the

593 Tertiary Moctezuma deposit, Mexico, to 436.5±27.1 and 502.8±46.0 (schmitterite) and

594 31.9±0.2 and 274.8±9.1 (moctezumite) ky old. These data suggest that erosion rate and

595 climate play a key role in the development and preservation of secondary Te minerals.

596 5.2 Tellurium deportment in soils and deeper regolith environments

597 In the regolith, immediately following the dissolution of tellurides, Te is generally bound by

598 sorption onto clay-sized soil particles rather than in minerals (Fairbrother et al., 2012; Goldfarb

599 et al., 2017; Hayes and Ramos, 2019). In particular, a strong association has been observed

600 between Fe3+ oxide minerals and Te (Qin et al., 2017). Te6+ can be incorporated into the 601 structures of Fe3+ oxides, whereas Te4+ tends to be bound more weakly to Fe3+ oxides by surface

602 interactions only (Qin et al., 2017). Both Qin et al. (2017) and Hayes and Ramos (2019) studied

603 Te speciation in tailings piles, meaning that subsequent studies are required to analyse Te

604 behaviour in different contexts. The extent to which nanoparticles (whether biogenic or

605 inorganic) of Te and/or tellurides are found in soils in Te-rich areas is not well constrained,

606 although several environmental species of microorganisms are known to produce Te

607 nanoparticles (see Section 6). We recommend further studies on the speciation and behaviour

608 of Te in soils and sediments in both natural and anthropogenic settings to shine further light on

609 the behaviour of Te, especially as its presence in the environment increases (Filella et al., 2019;

610 Presentato et al., 2019).

611 5.3 Anthropogenic tellurium

612 To date, the major anthropogenic activities involving Te are mining and ore processing (Te

613 being a by-product of Cu mining in particular) and fossil fuel burning, with emission

614 concentrations of Te on the order of mg/kg (Figure 5). Given the ~five-fold increase in Te

615 usage since 1940 (Nuss, 2019), environmental release of Te from Te-producing processes,

616 manufacturing Te-bearing industrial products, and subsequent decommissioning of these

617 products is expected to escalate. Highly toxic Te was also released during the Chernobyl and

618 Fukushima nuclear disasters; this is covered in the following section.

619 Currently, the production of CdTe solar cells consumes 40% of global Te output. Other

620 applications include thermoelectric production (30%), metallurgy/alloys (15%), rubber (5%),

621 and as a paint or pigment for glasses, enamels, and plastics (Anderson, 2019). Further uses of

622 Te include manufacture of CdTe quantum dots, readily synthesised by pyrolysis (Murray et al.,

623 1993). The semiconducting properties of these quantum dots make them useful for a wide

624 variety of medical (William et al., 2006) and electronics (Kumar and Kumar, 2015) 625 applications (toxicity of CdTe quantum dots discussed in the following section). CdTe solar

626 panels have their CdTe firmly encapsulated in protective casing, meaning that the operational

627 risk of toxic exposure to humans is virtually zero (Biver and Filella, 2016).

628 Nearly 90% of Te is produced by extraction from anode slimes using a series of

629 pyrometallurgical and hydrometallurgical operations to remove Se, Te and other precious

630 metals (Kyle et al., 2011; Makuei and Senanayake, 2018). The mined ore is subjected to milling,

631 flotation, smelting, casting and finally electrolysis in which Te is separated from Cu and

632 collects alongside other impurities as tellurides in the anode slime, now enriched 105 times

633 compared to the Te concentration in the Cu ore (Makuei and Senanayake, 2018). The methods

634 for recovering Te from the slimes are determined by chemical and phase composition and

635 content of associated metals. The tellurides are subjected to hydrometallurgical treatment either

636 by direct leaching of the raw slimes with sulphuric acid in the presence of oxygen (pressure)

637 or aeration (atmosphere), or by pressurised leaching in alkaline solution. Tellurium has also

638 been extracted from lead(–zinc) smelting processes (Makuei and Senanayake, 2018). Other

639 potential sources for Te extraction are flue dusts and gases generated during the smelting of

640 bismuth, copper, and gold ores (Kyle et al., 2011).

641 Tellurium waste comes in two main forms: Te released during mining and other manufacturing,

642 and Te waste produced after an end-product, such as a CdTe solar panel array, is

643 decommissioned. Tellurium contamination is common where trace amounts of Te in the

644 processing of materials like Cu ore result in the inadvertent release of Te to the environment

645 via Te-rich wastewaters (e.g. Kagami et al., 2012; Shibasaki et al., 1992). Other sources of Te

646 contamination to the environment during processing are (Cu) electroplating factories and

647 smelters (Chien and Han, 2009), electronics waste processors and recyclers (Shuva et al., 2016),

648 nickel refineries (Perkins, 2011), and sulphuric acid producers (Zonaro et al., 2017). Mining

649 activities and in particular tailings piles and dams may also leach Te, especially from Au mining, 650 or even the mining of other sulphide deposits, for instance at the Kawazu mine, Shizuoka,

651 Japan (Qin et al., 2017; see Figure 6, locality 18) and at Rodalquilar, Spain (Wray, 1998; see

652 Figure 6, locality 34). Sorption of Te is one method which may be used to remediate a Te-

653 contaminated site or waterway, through carbon-based sorbents (Dimpe and Nomngongo, 2017)

654 or biosorption (Piacenza et al., 2017), potentially recycling the sorbed Te for future use. Current

655 sources of Te contamination may be transformed into future sources of Te through recycling

656 programs (Shuva et al., 2016).

657 CdTe has a band gap of 1.45 eV at 300 K, making it perfectly matched to the peak of the solar

658 spectrum (Wu, 2004), leading to ever-increasing use in the solar panel industry. Discarded

659 cadmium telluride (CdTe) solar panels and to a lesser extent, other thermoelectric materials

660 like Bi2Te3 (with specific uses in the electronics industry) are likely to increase the

661 anthropogenic output of Te into the environment (Cyrs et al., 2014; Marwede and Reller, 2012;

662 Zeng et al., 2015). The dissolution of commonly used tellurides must be understood so that the

663 Te (and associated elements) do not become environmental contaminants (Ramos-Ruiz et al.,

664 2017b). Dealloying of CdTe occurs most efficiently when the decomposing solar panels are

665 exposed to oxidising, acidic conditions (Ramos-Ruiz et al., 2017b), with the reduction rate

666 decreasing monotonically with increasing pH (Biver and Filella, 2016). Unlike for some

667 chalcogenides, the CdTe dissolution rate does not stop completely under anoxic conditions,

668 and increases near-linearly with increasing dissolved oxygen. Bi2Te3 behaves markedly

669 differently, with no oxygen dependence, and a minimum rate of reduction at pH 5.3 (Biver and

670 Filella, 2016). These two examples show the importance of understanding the dissolution

671 regimes of individual tellurides, which may vary markedly from telluride to telluride. 672 5.4 Tellurium toxicity

673 Soluble Te oxyanions, the short-lived radioactive isotope 132Te, and nanoparticles of both

674 elemental Te and cadmium telluride (CdTe) are the most common toxic forms of Te. Soluble

675 forms of Te are more toxic than their insoluble counterparts based on the increased

676 bioavailability of Te from soluble compounds, with toxicity beginning at extremely low levels

677 for microbes (1 mg/L for tellurite; Presentato et al., 2019). In general, the tellurate anion is 2-

678 10 times less toxic than tellurite (Cunha et al., 2009). Both soluble oxyanions are most likely

679 to be encountered in contaminated wastewaters or around the weathering zones of Te deposits.

680 For humans, ca. 90% of ingested Te accumulates in the bones (Gerhardsson, 2015), while

681 accidental ingestion of microgram amounts of TeO2 or Na2TeO3 results in body odour and

4+ 682 garlic breath due to the metabolism of the Te oxysalts to gaseous dimethyl telluride, (CH3)2Te

683 (Cunha et al., 2009; Gerhardsson, 2015). Te is expected to be processed in a similar manner to

684 Se, although unlike Se, Te is not an essential micronutrient (Ogra, 2009; Presentato et al., 2019).

685 No cases of severe Te poisoning have been recorded, though workers at a Canadian silver

686 refinery exposed to Te during their work tended to report experiencing garlic odour when their

687 Te content surpassed 1 µmol Te per mol creatinine (Berriault and Lightfoot, 2011). The late

688 Alan Criddle (mineralogist at the Natural History Museum, London) contracted one of the few

689 documented recent cases of tellurium breath following a visit to the Au–Te deposit at

690 Moctezuma, Mexico. “[He] breathed in dust rich in the secondary tellurate ochres that occur

691 there. He said his breath stank so bad that dogs would run howling from him. He found it

692 difficult to live with himself for a few days” (oral communication, Ben Grguric).

693 One of the most toxic forms of Te is the short-lived, anthropogenically produced, radioactive

694 isotope, 132Te. 132Te is a toxic component of nuclear disaster contamination, and was the third-

695 most released radionuclide following the Fukushima Daiichi accident (Figure 10), with the 696 total released activity of 180 petabecquerel (PBq) only less than that from 131I and 133Xe (Gil-

697 Díaz, 2019). It is a β-particle emitter with a half-life of 3.2 days, decaying to 132I, which itself

698 is radioactive with a half-life of <3 hours and releases a β-particle to form the stable 132Xe. The

699 main toxicity mechanism of 132Te is the in corpore formation of the thyroid-critical element I,

700 as radioactive 132I. The 132I is subsequently transported to the thyroid, where it decays, causing

701 radiation damage (Drozdovitch et al., 2019). Exposure to 132Te is believed to have contributed

702 to the high incidence of thyroid cancers in people directly exposed to radiation after the

703 Fukushima Daiichi nuclear disaster (Drozdovitch et al., 2019). Additionally, 129mTe is also

704 produced in nuclear waste, and was detected in aerosols around Fukushima following the

705 meltdown (Foreman, 2015; Kanai, 2015) and may also be transported aqueously (Gil-Díaz et

706 al., 2019b). 129mTe decays via gamma radiation to 129Te, then follows a similar decay path to

707 132Te, i.e. via two β-particles to form stable 129Xe via radioactive 129I. However, 129I has a half-

708 life of 1.58 × 107 years, meaning 129I and thus 129mTe are of considerably less concern

709 biologically than 132Te and 132I, with 129mTe instead finding application as a 132Te signaller

710 (Tagami et al., 2013). The long half-life of 129I means most 129mTe produced in anthropogenic

711 nuclear reactions remains either in storage or in the environment today.

712 Although less toxic than their soluble and bioavailable oxyanion counterparts, Se and Te

713 nanoparticles are themselves toxic to many microorganisms. Many Te-resistant

714 microorganisms actively produce Te nanoparticles from Te oxyanions as a detoxifying

715 mechanism (see Section 6.3). The toxicity mechanism for non-resistant microorganisms is (1)

716 believed to be due to reaction of the nanoparticles with intracellular thiols, producing reactive

717 oxygen species (ROS) causing oxidative stress, much like the oxyanions of Se and Te (e.g.

718 Zonaro et al., 2015), and (2) may contribute to functional damage of cell membranes by

719 changing their composition (Pi et al., 2013). An advantage of nanoparticles over traditional

720 antimicrobial agents is that their high surface-to-volume ratios provide a larger area of 721 interaction with biological systems (Zonaro et al., 2015). Selenium and Te nanoparticles are

722 particularly noted for their antibiofilm ability, as many conventional antibiotics are more

723 effective against planktonic than biofilm bacteria, a problem which Se and Te nanoparticles

724 readily overcome (e.g. Zonaro et al., 2015). Tellurium nanoparticles produced from Bacillus

725 sp. BZ have been documented for their antifungal properties against the fungus Candida

726 albicans (Zare et al., 2014). Tellurium and Se nanoparticles could thus have future

727 antimicrobial and/or antifungal roles, with different morphologies to target different classes of

728 organism (Abo Elsoud et al., 2018; Estevam et al., 2017; Tran and Webster, 2013; Vaigankar

729 et al., 2018; Zonaro et al., 2015).

730 A different type of toxic Te-containing nanoparticle comes in the form of CdTe quantum dots,

731 which are now known to be cytotoxic (Chen et al., 2012; Lovrić et al., 2005), and are only used

732 in applications where contact with humans is minimal. The formation of ROS when CdTe

733 nanoparticles interact directly with the plasma membrane, mitochondria and nucleus of cells is

734 a key factor in their toxicity (Lovrić et al., 2005). Other toxicity factors are the release of soluble

735 Cd2+ ions and the overall intracellular distribution of the quantum dots (Chen et al., 2012).

736 Consequently, CdTe quantum dots must either be firmly encapsulated in protective coatings

737 for safe usage (e.g. glutathione; Zheng et al., 2007), although CdTe quantum dots have

738 sometimes been replaced by quantum dots formed from other materials (Li et al., 2009; Pons

739 et al., 2010).

740 6. BIOGEOCHEMISTRY OF TELLURIUM

741 Many essential processes in the biosphere are carried out by microbes, which generally operate

742 on quicker timescales than purely inorganic processes, and act across the microbial kingdoms,

743 interact with metals in many different ways (Ehrlich and Newman, 2009; Figure 11). Tellurium,

744 unlike the other non-transient chalcogens, is not known to be an essential biological nutrient 745 (Ogra, 2017), but Te is occasionally found substituting for S in the two sulphur-containing

746 amino acids cysteine and methionine (Anan et al., 2013; Ramadan et al., 1989). Additionally,

747 some microorganisms can respire tellurium oxyanions (e.g. Yurkov et al. 1996; further detail

748 provided below); this suggests that tellurium should possibly be noted in the list of biological

749 trace elements. In the environment, microorganisms typically interact with part per trillion

750 levels of Te, given its extreme rarity – especially in surface waters (see Section 4.1). Tellurium

751 has more similarity to S than other common biologically active elements – especially when

752 present in high concentrations, where it can interact with sulphate-specific enzymes such as

753 sulphate reductases (Ottosson et al., 2010) and transporters (Goff and Yee, 2017). More

754 recently, Te toxicity has been explored at a more detailed biochemical level, examining the

755 speciation of Te in different biological environments (e.g. Ogra, 2017; Turner et al., 2012).

756 While there is still conjecture on Te microbiology as applied to natural (including mineral

757 transformation) contexts, specific aspects of Te microbiology are well understood, particularly

758 its bioreduction (Taylor, 1999; Turner et al., 2012).

759 Broadly, Te biogeochemistry may be divided into biooxidation, biosorption/bioaccumulation,

760 and bioreduction (Figure 11). Biooxidation typically results in species which are more soluble

761 and toxic than their (usually solid) precursors. Coping mechanisms for dealing with high

762 (caused via organic or inorganic oxidation of reduced Te) concentrations of Te oxyanions

763 include biosorption, as well as bioprecipitation and biovolatilisation, which are both forms of

764 bioreduction.

765 6.1 Biooxidation (bioleaching)

766 Although there is no current evidence for direct environmental biooxidation of Te, recent

767 characterisation of ‘Se-oxidising bacteria’ and their role in biogeochemical Se cycling

768 (Nancharaiah and Lens, 2015) suggests that there may be ‘Te-oxidising bacteria’ in certain Te- 769 rich (micro)-environments. Se-oxidising bacteria were first identified as autotrophs, and are

770 mostly in the class of chemautotrophs, often thiobacilli. Biooxidation processes for Se are

771 typically 3-4 times slower than reduction, meaning that biologically mediated processes alone

772 result in locally greater amounts of reduced Se species (Nancharaiah and Lens, 2015). Se

773 oxidisers may themselves be capable of oxidising Te and tellurides to release Te oxyanions

774 back to the environment, but to our knowledge this potential process has not been studied.

775 Environmental oxidative processes initiated by microbes are commonly caused by ‘indirect’

776 mechanisms. Insoluble minerals do not typically pose any concern for microorganisms, as the

777 elements forming the minerals are not bioavailable (Ehrlich and Newman, 2009). One common

778 way metals are released in local (micro-)environments is that the bacteria use an ‘inert’

779 substrate to grow, and EPS or other biogenic molecules produced as the colony grows slowly

780 dissolve the surface of the substrate (Fairbrother et al., 2009; Reith et al., 2009; 2019). Another

781 common method occurs by the production of an oxidant in situ. Only a handful of acidophilic

782 chemolithotrophic bacteria – all S- and/or Fe-oxidisers that produce inorganic oxidants as a by-

783 product of their metabolism – have been studied for their oxidising behaviour applied to Te

784 compounds, with almost all of these studies aiming to enhance bioleaching (Choi et al., 2018;

785 Climo et al., 2000a; 2000b; Guo et al., 2012a; 2012b; Kim et al., 2015). Bioleaching is an

786 attractive method for extracting metals from sulphide ore as it uses gentler chemicals than

787 traditional leaching (Khaing et al., 2019). The leaching bacteria do not directly oxidise Te, but

788 instead Fe-oxidising bacteria oxidise Fe2+ to Fe3+ ions. In the presence of S-oxidising bacteria,

789 which tend to produce pH-lowering H+, the Fe3+ ions are then able to oxidise tellurides,

790 releasing the constituent metals into solution (Climo et al., 2000b). Equation 6.1 shows the

791 thermodynamically favourable (log K = 25.7 at 25°C, increasing to 29.0 at 60°C) oxidation of

792 calaverite by (biologically produced) ferric ions:

793 AuTe ( ) + 8Fe ( ) + 6H O Au( ) + 2H TeO ( ) + 6H ( ) + 8Fe ( ) (6.1) 3+ + + 2+ 2 𝑠𝑠 𝑎𝑎𝑎𝑎 2 ↔ 𝑠𝑠 3 3 𝑎𝑎𝑎𝑎 𝑎𝑎𝑎𝑎 𝑎𝑎𝑎𝑎 794 The most common S- or Fe-oxidising bacteria are capable of Te ore bioleaching, as discussed

795 in the following papers:

796 • Acidothiobacillus ferrooxidans (Choi et al., 2018; Kim et al., 2015)

797 • Leptospirillum ferrooxidans (Climo et al., 2000b)

798 • Thiobacillus ferrooxidans (Climo et al., 2000b; Guo et al., 2012b), T. thiooxidans, T.

799 caldus (Climo et al., 2000b)

800 In conclusion, in natural environments, Te and tellurides may be oxidised either inorganically

801 (e.g. in the presence of an oxidant like Fe3+) or organically (by as yet-uncharacterised Te

802 oxidisers). Currently, inorganic oxidation of tellurides is the best-defined way of releasing Te

803 to the environment, but the oxidants may be produced by biological means; Fe and S oxidisers

804 are both capable of leaching Te from tellurides in anthropogenic contexts. To date, no

805 microorganism has been described as purposefully dissolving tellurides or metallic Te via a

806 direct biooxidative process (Bonificio and Clarke, 2014).

807 6.2 Biosorption

808 Biosorption of Te is typically a precursor to bioreductive or bioaccumulative processes, as

809 microorganisms remove (soluble) Te from the environment in a process which begins with the

810 interaction of EPS with Te oxyanions (Figure 11). The biosorption mechanisms of soluble Te

811 oxyanions are not fully understood. One pathway for E. coli involves the tellurate anion

812 entering E. coli cells via the SulT-type sulphate transporter CysPUWA (Goff and Yee, 2017).

813 Removing the CysPUWA transporter in mutant strains of E. coli resulted in the accumulation

814 of less cellular Te, and higher resistance to Te compared to the wild-type strain (Goff and Yee,

815 2017). The tellurite anion appears to enter cells via different transporters, e.g. phosphate

816 transporters move tellurite into E. coli (Borghese et al., 2016a). In Rhodobacter capsulatus,

817 tellurite enters cells via the acetate permease RcActP2. RcActP2 seems to have particular 818 affinity to tellurite anions, as the acetate permease of E. coli is inactive to tellurite, but

819 expressing the RcActP2 permease of R. capsulatus in E. coli results in a fourfold increase in

820 the rate of tellurite uptake (Borghese et al., 2016a). Cells of species that are not resistant to Te

821 oxyanions will generally become poisoned when Te oxyanions are taken into the cell. The fatal

822 dose of Te may be bound in the dead microorganism’s biomass, preventing it from interacting

823 with other microorganisms. There is little prior literature examining the biosorption of Te as a

824 biochemical process, other than acknowledging that it is a precursor to bioreduction (Section

825 6.3) and bioaccumulation (Section 6.4), and this is an area which should be further examined.

826 More commonly, biosorption (followed by bioaccumulation) is simply discussed as a method

827 of bioremediation of areas Te-contaminated areas (Piacenza et al., 2017; see Section 6.5).

828 6.3 Bioreduction

829 Tellurium bioreduction comes in two main forms, namely bioprecipitation and biovolatilisation,

830 with the former being the more common Te detoxification mechanism. Bioprecipitation of Te

831 oxyanions to metallic Te was first noticed over a century ago, with the precipitative reduction

832 pathway taken by Te-resistant microorganisms first identified with optical microscopes, using

833 the black precipitate produced as a test for the presence of certain microbes (Corper, 1915;

834 King and Davis, 1914). Biovolatilisation of Te oxyanions was first noticed in the 19th century

835 due to the potent smell of volatile Te compounds. The conversion of Te oxyanions to alkylated,

836 gaseous Te compounds is mediated by S-adenosyl-methionine (SAM), as described by the

837 Challenger mechanism (Basnayake et al., 2001). Detoxification of soluble Te oxyanions by

838 reduction forms a large part of Te biogeochemistry (Presentato et al., 2019). Perhaps

839 symptomatic of the lack of understanding Te of biochemical mechanisms, few papers present

840 equations for the bio-reductive processes for Te in microorganisms. Simplified versions of the

841 two main bioreduction types are given here using the soluble tellurite anion as the starting

842 material: 843 ( ): ( ) ( ) ( . ) 𝟐𝟐− 𝟎𝟎 𝐁𝐁𝐁𝐁𝐁𝐁𝐩𝐩𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫𝐫 𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨 𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮 𝐓𝐓𝐓𝐓𝐓𝐓𝟑𝟑 𝒂𝒂𝒂𝒂 ↔ 𝐓𝐓𝐓𝐓 𝒔𝒔 𝟔𝟔 𝟐𝟐 844 ( ): ( ) ( ) ( ) ( . ) 𝟐𝟐− 𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁𝐁 𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨𝐨 𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮𝐮 𝐓𝐓𝐓𝐓𝐓𝐓𝟑𝟑 𝒂𝒂𝒂𝒂 ↔ 𝐂𝐂𝐂𝐂𝟑𝟑 𝟐𝟐𝐓𝐓𝐓𝐓 𝒈𝒈 𝟔𝟔 𝟑𝟑 845 The importance of determining the mechanism of tellurite toxicity is growing as anthropogenic

846 uses of Te increase (Ottosson et al., 2010); as a result, Te bioreduction has entered a scientific

847 ‘Renaissance period’ over the past decade (Presentato et al., 2019). Several research groups

848 (e.g. Goff and Yee, 2017; Turner et al., 2012) are continuing to study finer detail of microbial

849 reduction pathways of Te oxyanions. Figure 11 shows our summary of the currently known (or

850 postulated) biogeochemical processes for Te.

851 6.3.1 Mechanism of Te bioprecipitation

852 Bioprecipitation provides a method for removing toxic soluble Te oxyanions from the

853 environment, depositing Te as (relatively) inert nanoparticles (see Figure 11), following the

854 general trend that solid compounds are less toxic than soluble compounds. Additionally, Te-

855 resistant microorganisms are in general not adversely affected by the nanoparticles they

856 produce, even though for many microorganisms the nanoparticles themselves are toxic.

857 Bioprecipitation can occur as a result of microorganisms respiring Te oxyanions in anaerobic

858 respiration processes: some microorganisms are able to use either the tellurite or tellurate

859 anions as terminal electron acceptors. Under anoxic conditions, both Bacillus selenitireducens

860 and Sulphurospirillum barnesii are capable of respiring the Te oxyanions anaerobically,

861 turning a fatal concentration of Te oxyanions for many microorganisms into an evolutionary

862 advantage (Baesman et al., 2007).

863 Microorganisms capable of reducing the oxyanions of Te occur in a variety of extreme

864 environments, and a selection of the most important are listed in Table 4. A community of 123

865 separate Te-resistant bacteria was isolated from the Antarctic peninsula (Arenas et al., 2014), 866 where the resistance to Te oxyanions is thought to be endowed by cross-resistance to other

867 ROS generators like UV light. Other Te-resistant microorganisms were isolated from the

868 extreme high pressure and temperature environment of the Juan de Fuca Ridge black smoker

869 field, in the depths of the Pacific Ocean (Maltman et al., 2016; 2017). Tellurium and selenium

870 reducing bacteria are thought to have a symbiotic relationship with the tube worms which they

871 associate with near the Juan de Fuca Ridge black smoker field (Maltman et al., 2016; 2017).

872 Vent chimneys are a rich natural Te source (see Table 3), therefore microorganisms from these

873 environments are more likely to be Te resistant (Bonificio and Clarke, 2014). Similar

874 communities of Te oxyanion-reducing bacteria occur in a variety of anthropogenically

875 contaminated sites (Chien and Han, 2009; Kagami et al., 2012; Qin et al., 2017; Zonaro et al.,

876 2017; See Table 4). Highly saline lakes or springs like California’s Mono Lake (Figure 12;

877 Baesman et al., 2006; 2007; 2009) or Iran’s Neidasht spring (Etezad et al., 2009; Soudi et al.,

878 2009) also harbour Te-resistant organisms. The diversity of these localities shows that bacterial

879 cultures with varying degrees of Te resistance (for instance, different rates of reduction and

880 minimum inhibitory concentrations) exist in varied terrestrial environments.

881 The majority of microorganisms capable of reducing Te oxyanions are Gram-negative bacteria,

882 along with some alpha-Proteobacteria, Gram-positive bacteria (Presentato et al., 2016) and

883 fungi (Abo Elsoud et al., 2018; Gharieb et al., 1999). Interestingly, as well as containing more

884 representative species which can reduce Te oxyanions, Gram-negative bacteria are in general

885 more susceptible to Te oxyanion (especially tellurite) toxicity (Castro et al., 2008), as the

886 peptidoglycan-based cell wall of Gram-positive bacteria is better able to prevent Te oxyanions

887 from entering the bacterial cells.

888 The Te-sensitive E. coli was used in studies of how non-Te resistant microorganisms cope with

889 high levels of soluble Te (e.g. Wang et al., 2011). Some strains of E. coli have higher levels of

890 resistance to Te oxyanions than others, and genes encoding resistance in other microorganisms 891 have been expressed successfully in E. coli – giving the modified E. coli greater resistance to

892 Te oxyanions (e.g. Castro et al., 2009). The effects of elevated tellurite in E. coli include

893 decreased dNADH/NADH (Nicotinamide Adenine Dinucleotide) dehydrogenase activity,

894 alteration of oxidases, augmented lipid peroxidation, and Fe–S centre dismantling (Díaz-

895 Vásquez et al., 2015). Exposure to elevated levels of Te oxyanions for non-resistant organisms

896 usually proves fatal due to the generation of ROS and to an unbalancing of the thiol:redox cell

897 buffering system, (e.g. Arenas et al., 2014; Díaz-Vásquez et al., 2015). One method of reducing

898 tellurite toxicity is by exposure to the less toxic selenite, which protects E. coli from tellurite

899 damage in certain situations (Vrionis et al., 2015). The E. coli analogy provides valuable insight

900 into the mechanisms a typical non-resistant microorganism uses when exposed to Te oxyanions,

901 unlike the minority of microorganisms which are Te-resistant and have developed Te-

902 resistance pathways through their exposure to Te oxyanions.

903 Like E. coli, other microorganisms also use a NADH-dependent pathway to reduce tellurite e.g.

904 Salinicoccus iranensis (Alavi et al., 2014). Other Te-resistant microorganisms may have

905 specific tellurite reductases such as the E3 (dihydrolipoamide dehydrogenase) component of a

906 pyruvate dehydrogenase of Aeromonas Caviae (e.g. Castro et al., 2008; Castro et al., 2009),

907 the zinc- (Zn) and molybdenum- (Mo) containing enzyme of B. sp. STG-83 (Etezad et al., 2009)

908 and the two distinct enzymes responsible for Te and Se oxyanion reduction in the ER-Te-48

909 strain of bacteria isolated from the Juan de Fuca Ridge black smokers (Maltman et al., 2017).

910 The exact structure of specific Te-reducing enzymes is not fully understood. One tellurate

911 reductase enzyme in E. coli is likely to contain molybdopterin, as mutants with genes deleted

912 in the molybdopterin synthesis pathway were unable to reduce tellurate (Theisen et al., 2013)

913 – potentially this molybdopterin is the Mo-containing unit postulated by Etezad et al. (2009) in

914 B. sp. STG-83. Resistance to Te and other metals may also be associated with antibiotic 915 resistance due to co-resistance (i.e. genetic linkage) between the resistance genes (Argudín et

916 al., 2018).

917 Unsurprisingly, Te oxyanion-reducing bacteria operate best when in the presence of a reliable

918 source of organic carbon, typically also an electron donor which facilitates bioreductive

919 processes (e.g. acetate, lactate and pyruvate). The presence of redox mediator molecules

920 (generally quinone-based) typically results in greater efficiency of Te oxyanion reduction as

921 they can quickly transport electrons from cells to oxidised compounds (Ramos-Ruiz et al., 2016;

922 Van der Zee and Cervantes, 2009). The presence of other anions or molecules may also alter

923 the rates of Te oxyanion reduction. The pathways for reduction of selenite and tellurite are

924 typically rather different. Microorganisms that were studied for Te or Se oxyanion reduction

925 activity alone are expected to also reduce the other, but with different efficiencies and

926 maximum allowable concentrations of the oxyanions – as shown by comparative studies (e.g.

927 Etezad et al., 2009). The reduction rates of tellurite and tellurate anions are generally also

928 different for this reason. Tellurite is typically reduced faster, as the transition to elemental Te

929 requires two less electrons per Te atom than the reduction of tellurate. For instance, the tellurite

930 anion reduction rate by the methanogenic microbial consortium studied by Ramos-Ruiz et al.,

931 (2016) is seven times faster than the rate for tellurate: the reduction of tellurate to tellurite is

932 the rate-limiting step.

933 The presence of selenite increases tellurite reduction 13-fold by some bacterial cultures (Bajaj

934 and Winter, 2014) due to stimulation of tellurite reduction by parallel reduction with selenite.

935 Conversely, the white-rot fungus Phanerochaete chrysosporium a mixture of selenite and

936 tellurite has a more prohibitive effect on growth than either anion alone, indicating that

937 reduction mechanisms are organism-specific (Espinosa-Ortiz et al., 2017). In Shewanella

938 oneidensis MR-1, elemental chalcogen precipitates are produced extracellularly for Se, and

939 intracellularly for Te (Klonowska et al., 2005). Microorganisms which have been conditioned 940 (i.e. pre-exposed to low level concentrations of Te oxyanions) also tend to survive better when

941 exposed to larger levels of tellurite than microorganisms which were not conditioned to the Te

942 oxyanions (Presentato et al., 2016).

943 Additionally, some fungi and yeasts are also capable of bioreducing Te oxyanions, forming an

944 important mechanism of Te bioreduction. Gharieb et al. (1999) found that a species of

945 Fusarium reduced tellurite to elemental Te, and in the same study noted that Penicillium

946 citrinum reduced tellurite to both elemental Te nanoparticles and also to a volatile Te species

947 (see Section 6.3.3) The previously mentioned white-rot fungus, P. chrysosporium, is capable

948 of reducing both Se and Te oxyanions (Espinosa-Ortiz et al., 2017). Abo Elsoud et al. (2018)

949 analysed six different fungal isolates, and found that all were capable of producing elemental

950 Te, and new Te-reducing fungi are regularly identified (Liang et al., 2019). It is likely that

951 many more fungi will reduce Te oxyanions, particularly in telluriferous areas. Some fungi are

952 particularly noted for their biovolatilisation (see Section 6.3.3).

953 6.3.2 Morphology of biogenic Te nanoparticles

954 The morphology of precipitates formed via microbial reduction of Te oxyanions varies

955 considerably (Figure 13), and includes both intracellular and extracellular Te nanoparticles,

956 typically as rods or spheres (e.g. Baesman et al., 2009; Sepahei and Rashetnia, 2009;

957 Figure 13a). The mediating factors controlling whether the Te is produced intracellularly

958 and/or extracellularly seem to be organism-dependent, although in general the particles are

959 produced near the cytoplasm (White et al., 1995). Kagami et al. (2012) found that elemental

960 Te produced extracellularly can migrate away from the parent cell once produced. The size of

961 the nanoparticles often exceeds 100 nm (Jain et al., 2014). Redox mediators tend to promote

962 the production of extracellular Te nanostructures (Borghese et al., 2016b; Ramos-Ruiz et al.,

963 2016; Wang et al., 2011). Most studies describe Te oxyanion reduction under anoxic conditions, 964 where the reduction of an alternative oxidant to oxygen is preferable; however, Presentato et

965 al. (2016) describes the reliable synthesis of Te nanorods by an aerobic mechanism

966 (Figure 13b). Bioprecipitated compounds aside from elemental Te have only rarely been

967 reported, for instance the extracellular Se–Te composite nanoparticles formed by reduction of

968 a mixture of selenite and tellurite (Bajaj and Winter, 2014; Figure 13c).

969 6.3.3 Mechanism of Te biovolatilisation

970 Alkylation of p block elements (in particular methylation) is a common method by which cells

971 metabolise metals (Fatoki, 1997; Frankenberger Jr, 1993), and is a key method of releasing Te

972 to the atmosphere (Figure 5). Biovolatilisation typically accounts for less than 5% of total Te

973 oxyanion conversion, with the remainder of the Te bioprecipitated (see Figure 11; Ollivier et

974 al., 2008), i.e. there are no specific Te biovolatilisers. Biovolatilising microbes follow an

975 alkylation pathway, described by the Challenger mechanism (Basnayake et al., 2001). Early

976 experiments suggesting that S-adenosyl methionine (SAM) would bind to a telluro-methylase

977 enzyme (TehB) as part of the volatilisation process (Presentato et al., 2019) were verified by

978 the crystal-structure determination of TehB isolated from E. coli (Choudhury et al., 2011).

979 Biovolatilisation produces volatile, smelly gases containing covalent Te–C or Te–S bonds, the

980 simplest of which is dimethyl telluride [DMTe; (CH3)2Te]. Dimethyl ditelluride (DMDTe;

981 CH3TeTeCH3) is also common, while dimethyltellurenyl sulphide is rarer (DMTeS;

982 CH3TeSCH3) (see Figure 11; Ollivier et al., 2008; Zonaro et al., 2015). Organosulphur

983 compounds like dimethyl sulphide are also produced during the biovolatilisation processes

984 producing organotellurium compounds (Ollivier et al., 2008). Biovolatilisation thus results in

985 the natural release of Te to the atmosphere by the action of certain Te-resistant bacteria. This

986 process may occur in areas naturally rich in Te, or at contaminated anthropogenic sites. 987 Specific organisms which display natural volatilising behaviour, listed by alphabetical order of

988 genus then by species, are listed in Table 2 (DMTe, DMDTe and DMTeS in second column

989 from right). Penicillium molds are some of the only fungi studied for their biovolatilising

990 behaviour (White et al., 1995), with Penicillium citrinum biovolatilising as well as

991 bioprecipitating Te (Gharieb et al., 1999). One unexpected source of Se and Te volatiles (along

992 with volatile compounds of five other heavy metals) in certain local areas is duck manure

993 compost, the microbes in which proved capable of methylating and/or ethylating Se and Te

994 (Pinel-Raffaitin et al., 2008).

995 It is unclear whether biovolatilisation is truly a detoxification measure for microorganisms

996 which convert soluble Te to volatile forms, as unlike elemental Te, volatile organotellurium

997 compounds are not necessarily less toxic than their soluble Te oxyanion counterparts (White

998 et al., 1995). Nonetheless, even if the toxicity is similar, volatile compounds do have more

999 chance of migrating away from the microbes, suggesting that this mechanism is overall a

1000 detoxification measure (Basnayake et al., 2001). In highly Te-rich areas, the smell of onions or

1001 garlic may be detected in the air from the action of bioreducing microbes.

1002 6.3.4 Other mechanisms of Te detoxification

1003 Bioreduction is the most common method of Te detoxification, but it is not the only method by

1004 which microorganisms process high levels of soluble Te. Some bacteria (e.g.

1005 Erythromicrobium ezovicum and Roseococcus thiosulphatophilus) have been found to process

1006 Te oxyanions without using a reduction pathway, depending on the source of organic carbon

1007 available (Yurkov et al., 1996). These alternative methods of Te detoxification include tellurite

1008 efflux or complexing (Sepahei and Rashetnia, 2009; Yurkov et al., 1996), with complexing of

1009 Te oxyanions being a possible precursor to their bioaccumulation. The existence of 1010 microorganisms that resist high levels of Te oxyanions without using bioreductive mechanisms

1011 adds a further layer of complexity to the biogeochemistry of Te (Turner, 2001).

1012 6.4 Bioaccumulation

1013 Bioaccumulation begins for Te at the smallest biological level as Te-resistant microbes absorb

1014 soluble Te oxyanions and convert them to elemental Te by bioreduction. Elemental Te may

1015 accumulate in Te-resistant cells as Te nanoparticles (up to a maximum concentration before

1016 the precipitated Te blocks cellular processes from occurring) or as Te bound in proteins.

1017 Te nanoparticles are typically produced near cell boundaries (Turner et al., 2012), and some

1018 are released extracellularly (e.g. Bajaj and Winter, 2014; Borghese et al., 2016b) and may act

1019 as toxins for other microorganisms – in a different fashion to the toxicity mechanism for soluble

1020 Te oxyanions (e.g. Abo Elsoud et al., 2018). In general, heavy metals and other toxins are

1021 concentrated up the food chain; plants and animals have higher levels of Te than the

1022 surrounding environment.

1023 Some onion and garlic family (Allium) plants owe their distinctive smell to organosulphur

1024 compounds – and to lesser extents to organoselenium and organotellurium compounds.

1025 Although Te conversion in these species is not an essential feature of their metabolism, plants

1026 like Allium sativum are capable of incorporating Te into two usually S-containing amino acids,

1027 cysteine and methionine (Anan et al., 2013), with some plants in the Allium family containing

1028 extreme levels of Te enrichment up to 300 mg/kg (Dunn, 2011). However in general, Te levels

1029 in plants do not exceed 1 mg/kg, even in telluriferous soils (Cowgill, 1988), and commonly

1030 plants contain less than 0.02 mg/kg Te (Dunn, 2011). The flowers of plants generally contain

1031 the most Te, and tree leaves contain more Te than branches (Cowgill, 1988; Dunn, 2011).

1032 Bioaccumulation of Te provides one potential sink for Te in the natural environment. The rarity

1033 of Te means that natural bioaccumulation only occurs to a significant extent in areas with 1034 naturally or anthropogenically raised levels of Te. As a relatively reactive element, Te is

1035 unlikely to remain bioaccumulated for long periods of time, especially as biogenically

1036 produced nanoparticles (see below).

1037 6.5 Applications

1038 All of the common biotransformations of Te have some practical uses, which are briefly

1039 discussed in this section. Biooxidation of gold tellurides has become a relatively common pre-

1040 treatment step in gold mining. Gold tellurides host a significant amount of the gold grade in

1041 many deposits, but traditional leaching using cyanide, thiourea, or ammoniacal thiosulfate

1042 solutions are not efficient for gold tellurides; thus pre-treatment stages have been introduced

1043 prior to leaching, the most commonly used being energy intensive high temperature roasting

1044 (Zhao et al., 2010). Adding a culture of oxidising microbes to Au-telluride ore piles may allow

1045 release of higher amounts of metals than would otherwise be possible (Climo et al., 2000a;

1046 2000b), while at the opposite end of the process, adding a culture of reducing microbes to waste

1047 streams could allow recovery of toxic elements, preventing them from becoming pollutants

1048 (Ramos-Ruiz et al., 2017a).

1049 Biosorption of a variety of heavy metals has been discussed as an environmentally friendly

1050 method for their remediation (Alluri et al., 2007; Banerjee et al., 2018; Dhankhar and Hooda,

1051 2011; Gavrilescu, 2004; Piacenza et al., 2017; White et al., 1995). Using either living or dead

1052 biomass to entrap metals from polluted streams is particularly viable for large-scale low-level

1053 contamination, when sorption using more toxic chemicals is less effective (Gavrilescu, 2004).

1054 Currently, such techniques have not been implemented for Te sorption on an industrial level

1055 However, the most likely area of future application involves the biosorption of Te (and Cd)

1056 released from decommissioned CdTe solar panels (Alluri et al., 2007; Dhankhar and Hooda,

1057 2011; Rajwade and Paknikar, 2003). Biosorption may one day be used for both remediation of 1058 a contaminated area and recycling, by collecting the sorbed nanoparticles and repurposing them

1059 for other uses (Dhankhar and Hooda, 2011; Piacenza et al., 2017). Two studies published near-

1060 concurrently in 2017 both outlined a preliminary design for an Upflow Anaerobic (granular)

1061 Sludge Bed (UASB) for Te biosorption. Both papers theorised that their model reactor beds

1062 could be scaled up to recycle Te-containing wastewaters as nanoparticles of elemental Te (Mal

1063 et al., 2017; Ramos-Ruiz et al., 2017a). The UASBs provide a double benefit of cleaning the

1064 wastewater and also potentially result in a recycled supply of Te. Mal et al. (2017) found that

1065 their model reactor was able to remove 90% of the tellurite from 20 mg/L tellurite solutions,

1066 with most of this Te associating with the granular sludge as elemental Te. 78% of this Te was

1067 reclaimed from the sludge by an EPS method. Ramos-Ruiz et al. (2017) obtained comparable

1068 percentages of continuous removal of Te from 20 mg/L tellurite solutions, ranging from 83-

1069 96% without a redox mediator (riboflavin in this case, better known as vitamin B2) to assist in

1070 the electron transfer, and greater than 99.5% efficiency with the redox mediator. Similar

1071 UASBs have also been designed and described for Se alone (e.g. Jain et al., 2016). More

1072 recently, a UASB capable of bioreducing selenite and tellurite simultaneously was described

1073 (Wadgaonkar et al., 2018). Biosorption – and often subsequently, bioprecipitation – thus forms

1074 an intermediate step in the removal of soluble Te from the environment, and on a larger scale

1075 may gain prominence in future as a method of removing and recycling Te from waste materials

1076 (Nancharaiah et al., 2016).

1077 Tellurium and Se nanoparticles can be produced via bioreduction in morphologies that can be

1078 difficult to obtain via inorganic means (Bansal et al., 2012; Zonaro et al., 2017). Biosynthesis

1079 also has environmental advantages, typically requiring lower amounts of toxic chemicals than

1080 alternative methods (Presentato et al., 2016). As well as antimicrobial applications (see Section

1081 5.4), the nanoparticles may potentially be used in a variety of highly accurate detecting

1082 applications, such as for detecting hydrogen peroxide (Manikandan et al., 2017; Wang et al., 1083 2010), chlorine gas (Sen et al., 2009) and Hg2+ cations (Wei et al., 2011). Further applications

1084 are noted for Se and Te nanoparticles by making use of their photocatalytic degradation

1085 properties (Vaigankar et al., 2018).

1086 7. A TELLURIUM BIOGEOCHEMICAL CYCLING MODEL

1087 7.1 An integrated Te cycling model – comparison with Se

1088 The results of this analysis are summarized in the integrated Te cycling model presented in

1089 Figure 5, linking inorganic and organic processes. Our Te cycle is based on those known for

1090 other elements, especially Se, and on our current understanding of the geochemistry and

1091 microbial ecology of Te. Elemental cycling has long been known for biologically essential

1092 elements, most notably the carbon (C), nitrogen (N) and sulphur (S) cycles. Even elements

1093 which were long assumed to be geochemically inert are involved in complex biogeochemical

1094 cycling (Stolz, 2017), including Au and Pt (Reith et al., 2014; 2007). Te is the last non-transient

1095 chalcogen (any attempts to define such a cycle for polonium (Po) would be essentially

1096 meaningless) without a detailed biogeochemical cycling description, following the description

1097 of the Se cycle by Nancharaiah and Lens (2015).

1098 The Te cycle begins with the processing of Te-rich crustal rock through either magmatism or

1099 hydrothermal processes (Figure 5), leading to the formation of Te-rich deposits (see Section 4)

1100 or near fumaroles, volcanogenic sulphur (Figure 5). The ore from these deposits may be

1101 processed by mining and smelting, most likely for the Au or Cu content rather than for recovery

1102 of Te itself, or the Te may be released to the environment by weathering processes, especially

1103 if anthropogenic activities have exposed more of the ore (Figure 5). Weathering and emission

1104 of Te to the environment during mining, usage and recycling/breakdown may lead to solid,

1105 aqueous or gaseous forms of Te, depending on the processes involved. Solid forms include Te

1106 sorbed onto clays and Fe oxides in soils (Figure 5), oxidative dissolution leads to aqueous Te 1107 oxyanions (Figure 5), and volatilisation (mostly biological, except at high temperatures during

1108 earlier smelting or mining processing steps) leads to gaseous forms of Te (Figure 5). Deposition

1109 into sediments and dissolution into groundwater result in higher Te concentrations than occur

1110 in freshwater and ocean water (Figure 5). Te also sparingly enters biomass through

1111 microorganisms, though as Te is nonessential for life, its intake is incidental compared to the

1112 minute but essential amounts of Se that all organisms must absorb. The breakdown of these

1113 organisms over millions of years leads to the presence of Se and Te in coal at levels greater

1114 than their crustal abundances (Figure 5), and burning coal is one mode of Te and Se release to

1115 the atmosphere.

1116 The bacterium in Figure 11 shows the biogeochemical processes present for Te in full.

1117 Nancharaiah and Lens (2015) postulate that Se is cycled between oxic and anoxic environments

1118 in natural environments, and influences carbon and nitrogen mineralisation processes through

1119 bacterial anaerobic respiration. As is the case for Te, Se bioreduction converts Se from soluble

1120 Se oxyanions to elemental Se and volatile organo-selenium compounds. Selenium oxidisers

1121 provide one method of release of Se from elemental Se and selenides, allowing solubilised Se

1122 to again travel in waterways until a reduction source (selenium resistant microbes and soluble

1123 inorganic cations which precipitate Se oxyanions) is encountered, whereas Te oxidisers are

1124 currently only postulated to exist. The relation between the Te and Se cycles may be even

1125 closer, with some microorganisms capable of acting in similar ways on both Se and Te species

1126 – for instance Se and Te reducers both produce either elemental chalcogen nanoparticles or

1127 volatile organochalcogens (Wallschläger and Feldmann, 2010). In summary, the processes

1128 governing the Te biogeochemical cycle are clear, but the extent to which microbially-catalysed

1129 pathways for reduction, oxidation or other processes predominate in surficial environments is

1130 not yet known, and will form the core of future work on the environmental geochemistry of Te. 1131 7.2 Tellurium dispersion around Au-Te deposits

1132 In Figure 14, we apply our cycling model to the example of elemental dispersion of Te around

1133 a Au–Te deposit. We have chosen to discuss this example of Te cycling, as (1) Te and Au are

1134 typically found together, in association with metal sulphides; (2) the Au cycle is already well

1135 understood (Rea et al., 2018; Sanyal et al., 2019; Shuster and Reith, 2018), (3) Te may be used

1136 as a pathfinder for Au through application of their linked biogeochemical cycles, and (4) this

1137 is an important analogue for predicting the fate of anthropogenic Te contamination.

1138 This model describes the movement of Te and Au through the environment around a buried

1139 Au–Te hydrothermal vein. Gold and Te occur as gold tellurides, along with small Au nuggets,

1140 ‘invisible Au’ associated with other primary minerals, and elemental Te (Sung et al., 2009).

1141 Once these minerals reach the surface and interact with groundwater within the saprolith, they

1142 may begin to undergo dissolution reactions, in particular inorganic acidic weathering (see

1143 Section 5.1). Passive oxidation by different classes of microorganisms may also have an effect

1144 on the release of Au and Te to the soil. As soluble species, Au and Te in surface aqueous

1145 solutions are toxic to macro- and microorganisms in sufficiently high concentrations. Once

1146 solubilised, reprecipitation and dissolution reactions occur in a cyclical fashion, and other

1147 chemical species such as Cu2+, Pb2+, Fe3+, Cl- interact with soluble forms of Te. Tellurium

1148 released into natural waters as tellurite may undergo further oxidation to tellurate. As mobile

1149 Te oxyanions, Te may be transported away from the weathering zone of the Te deposit by

1150 groundwater. Eventually, Te may be removed from environmental aqueous solution by three

1151 major methods:

1152 (1) Purely inorganic methods (precipitation by a cation, possibly leading to secondary

1153 mineralisation). This scenario is especially prominent if pH levels increase towards neutral

1154 further from weathering sites, lowering the solubility of soluble Te oxyanions. 1155 (2) Microbial bioreduction (formation of Te nanoparticles or gaseous organotellurium

1156 compounds, especially in areas where the microorganisms display Te resistance). Some

1157 microorganisms have been shown to successfully detoxify both Se and Te oxyanions,

1158 suggesting that this is one area where the Se and Te cycles may overlap (Bajaj and Winter,

1159 2014; Espinosa-Ortiz et al., 2017). The plethora of studies on how microorganisms interact

1160 with soluble Te in controlled laboratory settings gives us an insight into how such

1161 microorganisms might interact with soluble Te in natural environments. Bioprecipitated Te

1162 nanoparticles are relatively reactive, although if they aggregate together the rate of reaction is

1163 slowed. The elemental Te nanoparticles produced by bioprecipitation may remain insoluble, or

1164 depending on conditions could be oxidised again to soluble Te species. Alkylated forms of Te

1165 produced by biovolatilisation, although produced as minority products in bioreductive

1166 processes, can travel as airborne material (although organotellurium compounds are denser

1167 than air, meaning these compounds are unlikely to travel long distances), spreading Te away

1168 from natural or anthropogenic Te rich areas. Other methods of Te release to the atmosphere

1169 include anthropogenic methods (e.g. burning Te-containing coal) and the release of Te-

1170 containing volcanic gases.

1171 (3) Removal of Te and Au from aqueous solutions by macrobiota, although in sufficient

1172 amounts this may result in health problems for the new host organisms. This effect is most

1173 prominent in metal-rich haloes around ore deposits.

1174 Eventually Te returns to the regolith, either as atmospheric organotellurium compounds

1175 interacting with soils to form aqueous or solid forms of Te, or by release of Te and Au from

1176 their hosts. Microbes and fungi are likely to be involved in these conversion steps, from where

1177 Te may continue its biogeochemical cycle. Thus, through a variety of inorganic and biological

1178 processes, Te may be cycled through the environment, with these cycles especially active near

1179 locally tellurium-rich areas (e.g. Au mining sites) or anthropogenically contaminated areas (e.g. 1180 Cu refining plants or sulphuric acid factories). We expect that future advances in this area will

1181 lead to a more complete description of the biogeochemical Te cycle, including the percentage

1182 split between inorganic and biological pathways for the same processes, thus providing

1183 valuable insight into the environmental mobility of a rare, yet important element.

1184 ACKNOWLEDGEMENTS

1185 The authors acknowledge support funding provided to OPM by an Australian

1186 Government Research Training Program (RTP) Scholarship, a Monash Graduate Excellence

1187 Scholarship (MGES) and a Monash-Museums Victoria Scholarship (Robert Blackwood). The

1188 authors further acknowledge The Ian Potter Foundation grant ‘tracking tellurium’ to SJM.

1189 Further funding support was provided Natural Environment Research Council (UK) grant

1190 NE/M010848/1 in the Security of Supply of Minerals programme to DJS. The authors would

1191 like to acknowledge the ARC Research Hub on Australian Copper-Uranium (project number:

1192 IH130200033), funded by the Australian Research Council, BHP Olympic Dam and the South

1193 Australian Department of State Development; for their support and assistance. We are grateful

1194 to Brent Thorne (Figure 1), Victor Okrugin (Figure 8a) and Stefan Ansermet (Figure 9c) for

1195 providing images of Te minerals.

1196 FOOTNOTES

#1 1197 The only exception to this rule is goldfieldite, Cu10Te4S13, which has Tellurium (IV)

1198 surrounded by three S atoms.

1199 #2 Note that all numbers of total minerals in this section include overlaps as some Te minerals

1200 have complex chemical compositions. Montbrayite, for instance, has the recently revised

1201 formula [(Au,Ag,Sb,Pb,Bi)23(Te,Sb,Pb,Bi)38; Bindi et al., 2018]. One branch of Te

1202 biogeochemistry studies applications for biogenic Te nanoparticles. In those cases, sizes less 1203 than 30 nm can be desirable due to the large increases in surface area for lower particle

1204 diameters, rather than particles which are larger than 100 nm.

1205

1206 1207 REFERENCES

1208 Abo Elsoud, M.M., Al-Hagar, O.E.A., Abdelkhalek, E.S. and Sidkey, N.M., 2018. Synthesis and 1209 investigations on tellurium myconanoparticles. Biotechnology Reports, 18: e00247. 1210 Alavi, S., Amoozegar, M.A. and Khajeh, K., 2014. Enzyme(s) responsible for tellurite reducing 1211 activity in a moderately halophilic bacterium, Salinicoccus iranensis strain QW6. 1212 Extremophiles, 18(6): 953-961. 1213 Alluri, H.K., Ronda, S.R., Settalluri, V.S., Bondili, J.S., Suryanarayana, V. and Venkateshwar, P., 1214 2007. Biosorption: An eco-friendly alternative for heavy metal removal. African 1215 journal of Biotechnology, 6(25): 2924-2931. 1216 Altree-Williams, A., Pring, A., Ngothai, Y. and Brugger, J., 2015. Textural and compositional 1217 complexities resulting from coupled dissolution–reprecipitation reactions in 1218 geomaterials. Earth-Science Reviews, 150: 628-651. 1219 Amatya, R. and Ram, R.J., 2012. Trend for thermoelectric materials and their earth abundance. 1220 Journal of electronic materials, 41(6): 1011-1019. 1221 Amoozegar, M.A., Ashengroph, M., Malekzadeh, F., Razavi, M.R., Naddaf, S. and Kabiri, M., 1222 2008. Isolation and initial characterization of the tellurite reducing moderately 1223 halophilic bacterium, Salinicoccus sp. strain QW6. Microbiological research, 163(4): 1224 456-465. 1225 Anan, Y., Yoshida, M., Hasegawa, S., Katai, R., Tokumoto, M., Ouerdane, L., Łobiński, R. and 1226 Ogra, Y., 2013. Speciation and identification of tellurium-containing metabolites in 1227 garlic, Allium sativum. Metallomics, 5(9): 1215-1224. 1228 Anders, E. and Grevesse, N., 1989. Abundances of the elements: Meteoritic and solar. 1229 Geochimica et Cosmochimica acta, 53(1): 197-214. 1230 Anderson, C.S., 2019. Tellurium. USGS Mineral Commodity Summaries, https://prd-wret.s3- 1231 us-west-2.amazonaws.com/assets/palladium/production/atoms/files/mcs-2019- 1232 tellu.pdf. 1233 Andreeva, E.D., Matsueda, H., Okrugin, V.M., Takahashi, R. and Ono, S., 2013. Au–Ag–Te 1234 Mineralization of the Low ‐ Sulfidation Epithermal Aginskoe Deposit, Central 1235 Kamchatka, Russia. Resource Geology, 63(4): 337-349. 1236 Arenas, F.A., Pugin, B., Henríquez, N.A., Arenas-Salinas, M.A., Díaz-Vásquez, W.A., Pozo, M.F., 1237 Muñoz, C.M., Chasteen, T.G., Pérez-Donoso, J.M. and Vásquez, C.C., 2014. Isolation, 1238 identification and characterization of highly tellurite-resistant, tellurite-reducing 1239 bacteria from Antarctica. Polar Science, 8(1): 40-52. 1240 Argudín, M., Hoefer, A. and Butaye, P., 2018. Heavy metal resistance in bacteria from animals. 1241 Research in veterinary science, 122: 132-147. 1242 Armstrong, J.G., Parnell, J., Bullock, L.A., Perez, M., Boyce, A.J. and Feldmann, J., 2018. 1243 Tellurium, selenium and cobalt enrichment in Neoproterozoic black shales, Gwna 1244 Group, UK: Deep marine trace element enrichment during the Second Great 1245 Oxygenation Event. Terra Nova, 30(3): 244-253. 1246 Asadi, H., Voncken, J., Kühnel, R. and Hale, M., 2000. Petrography, mineralogy and 1247 geochemistry of the Zarshuran Carlin-like gold deposit, northwest Iran. Mineralium 1248 Deposita, 35(7): 656-671. 1249 Ba, L.A., Döring, M., Jamier, V. and Jacob, C., 2010. Tellurium: an element with great biological 1250 potency and potential. Organic & biomolecular chemistry, 8(19): 4203-4216. 1251 Bae, E.J., Kang, Y.H., Jang, K.-S. and Cho, S.Y., 2016. Enhancement of thermoelectric properties 1252 of PEDOT: PSS and tellurium-PEDOT: PSS hybrid composites by simple chemical 1253 treatment. Scientific reports, 6: 18805. 1254 Baesman, S.M., Bullen, T., Dewald, J., Zhang, D., Curran, S., Islam, F., Beveridge, T. and 1255 Oremland, R., 2006. Formation of Unique Tellurium Nanocrystals with Anaerobic 1256 Growth of Bacillus selenitireducens and Sulfurospirillum barnesii using Te-oxyanions 1257 as Electron Acceptors, AGU Fall Meeting Abstracts. 1258 Baesman, S.M., Bullen, T.D., Dewald, J., Zhang, D., Curran, S., Islam, F.S., Beveridge, T.J. and 1259 Oremland, R.S., 2007. Formation of tellurium nanocrystals during anaerobic growth of 1260 bacteria that use Te oxyanions as respiratory electron acceptors. Applied and 1261 Environmental Microbiology, 73(7): 2135-2143. 1262 Baesman, S.M., Stolz, J., Kulp, T. and Oremland, R.S., 2009. Enrichment and isolation of 1263 Bacillus beveridgei sp. nov., a facultative anaerobic haloalkaliphile from Mono Lake, 1264 California, that respires oxyanions of tellurium, selenium, and arsenic. Extremophiles, 1265 13(4): 695-705. 1266 Bailey, R.T., 2017. Selenium contamination, fate, and reactive transport in groundwater in 1267 relation to human health. Hydrogeology Journal, 25(4): 1191-1217. 1268 Bajaj, M. and Winter, J., 2014. Se (IV) triggers faster Te (IV) reduction by soil isolates of 1269 heterotrophic aerobic bacteria: formation of extracellular SeTe nanospheres. 1270 Microbial cell factories, 13(1): 168. 1271 Banerjee, A., Jhariya, M.K., Yadav, D.K. and Raj, A., 2018. Micro-remediation of Metals: A New 1272 Frontier in Bioremediation. In: C.M. Hussain (Editor), Handbook of Environmental 1273 Materials Management. Springer International Publishing, Cham, pp. 479-513. 1274 Bansal, V., Bharde, A., Ramanathan, R. and Bhargava, S.K., 2012. Inorganic materials using 1275 ‘unusual’microorganisms. Advances in Colloid and Interface Science, 179: 150-168. 1276 Basnayake, R.S., Bius, J.H., Akpolat, O.M. and Chasteen, T.G., 2001. Production of dimethyl 1277 telluride and elemental tellurium by bacteria amended with tellurite or tellurate. 1278 Applied organometallic chemistry, 15(6): 499-510. 1279 Bateman, R. and Hagemann, S., 2004. Gold mineralisation throughout about 45 Ma of 1280 Archaean orogenesis: protracted flux of gold in the Golden Mile, Yilgarn craton, 1281 Western Australia. Mineralium Deposita, 39(5-6): 536-559. 1282 Baturin, G.N., 2012. The geochemistry of manganese and manganese nodules in the ocean, 1283 Vol 2. Springer Science & Business Media. 1284 Bauer, D.J., Diamond, D.B., Li, J., 2010. Critical Materials Strategy. U.S. Department of Energy, 1285 https://www.hsdl.org/?view&did=703261. 1286 Belousov, I., Large, R., Meffre, S., Danyushevsky, L., Steadman, J. and Beardsmore, T., 2016. 1287 Pyrite compositions from VHMS and orogenic Au deposits in the Yilgarn Craton, 1288 Western Australia: Implications for gold and copper exploration. Ore Geology Reviews, 1289 79: 474-499. 1290 Belzile, N. and Chen, Y.-W., 2015. Tellurium in the environment: A critical review focused on 1291 natural waters, soils, sediments and airborne particles. Applied Geochemistry, 63: 83- 1292 92. 1293 Bennett, K.T., Bone, S.E., Akin, A.C., Birnbaum, E.R., Blake, A.V., Brugh, M., Daly, S.R., Engle, 1294 J.W., Fassbender, M.E. and Ferrier, M.G., 2019. Large-Scale Production of 119mTe and 1295 119Sb for Radiopharmaceutical Applications. ACS central science, 5(3): 494-505. 1296 Berriault, C.J. and Lightfoot, N.E., 2011. Occupational tellurium exposure and garlic odour. 1297 Occupational Medicine, 61(2): 132-135. 1298 Bindi, L. and Biagioni, C., 2018. A crystallographic excursion in the extraordinary world of 1299 minerals: the case of Cu- and Ag-rich sulfosalts. Acta Crystallographica Section B, 74(6): 1300 527-538. 1301 Bindi, L., Paar, W.H. and Lepore, G.O., 2018. Montbrayite,(Au,Ag,Sb,Pb,Bi)23(Te,Sb,Pb,Bi)38, 1302 from the Robb-montbray Mine, Montbray, Quebec: Crystal Structure and Revision of 1303 the Chemical Formula. The Canadian Mineralogist: canmin. 1700095. 1304 Binns, R., Dotter, L. and Blacklock, K., 2004. Chemistry of Borehole Fluids Collected at 1305 PACMANUS, Papua New Guinea, OPD Leg 193. 1306 Biver, M. and Filella, M., 2016. Bulk dissolution rates of cadmium and bismuth tellurides as a 1307 function of pH, temperature and dissolved oxygen. Environmental Science & 1308 Technology, 50(9): 4675-4681. 1309 Blundy, J. and Wood, B., 1994. Prediction of crystal–melt partition coefficients from elastic 1310 moduli. Nature, 372(6505): 452. 1311 Boni, M., Gilg, H.A., Aversa, G. and Balassone, G., 2003. The" calamine" of southwest Sardinia: 1312 Geology, mineralogy, and stable isotope geochemistry of supergene Zn mineralization. 1313 Economic Geology, 98(4): 731-748. 1314 Bonificio, W.D. and Clarke, D.R., 2014. Bacterial recovery and recycling of tellurium from 1315 tellurium ‐ containing compounds by P seudoalteromonas sp. EPR 3. Journal of 1316 applied microbiology, 117(5): 1293-1304. 1317 Borghese, R., Canducci, L., Musiani, F., Cappelletti, M., Ciurli, S., Turner, R.J. and Zannoni, D., 1318 2016a. On the role of a specific insert in acetate permeases (ActP) for tellurite uptake 1319 in bacteria: Functional and structural studies. Journal of Inorganic Biochemistry, 163: 1320 103-109. 1321 Borghese, R., Brucale, M., Fortunato, G., Lanzi, M., Mezzi, A., Valle, F., Cavallini, M. and 1322 Zannoni, D., 2016b. Extracellular production of tellurium nanoparticles by the 1323 photosynthetic bacterium Rhodobacter capsulatus. Journal of Hazardous Materials, 1324 309: 202-209. 1325 Bowell, R., 1992. Supergene gold mineralogy at Ashanti, Ghana: implications for the 1326 supergene behaviour of gold. Mineralogical Magazine, 56(385): 545-560. 1327 Braukmüller, N., Wombacher, F., Funk, C. and Münker, C., 2019. Earth’s volatile element 1328 depletion pattern inherited from a carbonaceous chondrite-like source. Nature 1329 Geoscience, 12(7): 564-568. 1330 Brugger, J., Etschmann, B.E., Grundler, P.V., Liu, W., Testemale, D. and Pring, A., 2012. XAS 1331 evidence for the stability of polytellurides in hydrothermal fluids up to 599°C, 800 bar. 1332 American Mineralogist, 97(8-9): 1519-1522. 1333 Brugger, J., Liu, W., Etschmann, B., Mei, Y., Sherman, D.M. and Testemale, D., 2016. A review 1334 of the coordination chemistry of hydrothermal systems, or do coordination changes 1335 make ore deposits? Chemical Geology, 447: 219-253. 1336 Bullock, L., Parnell, J., Perez, M. and Feldmann, J., 2017. Tellurium Enrichment in Jurassic Coal, 1337 Brora, Scotland. Minerals, 7(12): 231. 1338 Butler, I. and Nesbitt, R., 1999. Trace element distributions in the chalcopyrite wall of a black 1339 smoker chimney: insights from laser ablation inductively coupled plasma mass 1340 spectrometry (LA–ICP–MS). Earth and Planetary Science Letters, 167(3-4): 335-345. 1341 Castro, M.E., Molina, R., Díaz, W., Pichuantes, S.E. and Vásquez, C.C., 2008. The 1342 dihydrolipoamide dehydrogenase of Aeromonas caviae ST exhibits NADH-dependent 1343 tellurite reductase activity. Biochemical and Biophysical Research Communications, 1344 375(1): 91-94. 1345 Castro, M.E., Molina, R.C., Díaz, W.A., Pradenas, G.A. and Vásquez, C.C., 2009. Expression of 1346 Aeromonas caviae ST pyruvate dehydrogenase complex components mediate tellurite 1347 resistance in Escherichia coli. Biochemical and biophysical research communications, 1348 380(1): 148-152. 1349 Cepedal, A., Fuertes-Fuente, M., Martin-Izard, A., Gonzalez-Nistal, S. and Rodriguez-Pevida, 1350 L., 2006. Tellurides, selenides and Bi-mineral assemblages from the Río Narcea Gold 1351 Belt, Asturias, Spain: genetic implications in Cu–Au and Au skarns. Mineralogy and 1352 Petrology, 87(3-4): 277-304. 1353 Chasteen, T.G. and Bentley, R., 2003. Biomethylation of selenium and tellurium: 1354 microorganisms and plants. Chemical reviews, 103(1): 1-26. 1355 Chasteen, T.G., Fuentes, D.E., Tantaleán, J.C. and Vásquez, C.C., 2009. Tellurite: history, 1356 oxidative stress, and molecular mechanisms of resistance. FEMS Microbiology 1357 Reviews, 33(4): 820-832. 1358 Chen, N., He, Y., Su, Y., Li, X., Huang, Q., Wang, H., Zhang, X., Tai, R. and Fan, C., 2012. The 1359 cytotoxicity of cadmium-based quantum dots. Biomaterials, 33(5): 1238-1244. 1360 Chen, R., Xu, D., Guo, G. and Gui, L., 2002. Silver telluride nanowires prepared by DC 1361 electrodeposition in porous anodic alumina templates. Journal of Materials Chemistry, 1362 12(8): 2435-2438. 1363 Chen, Y.-W., Alzahrani, A., Deng, T.-L. and Belzile, N., 2016. Valence properties of tellurium in 1364 different chemical systems and its determination in refractory environmental samples 1365 using hydride generation–atomic fluorescence spectroscopy. Analytica chimica acta, 1366 905: 42-50. 1367 Cheng, Z., Zhang, Z., Chai, F., Hou, T., Santosh, M., Turesebekov, A. and Nurtaev, B., 2018. 1368 Carboniferous porphyry Cu–Au deposits in the Almalyk orefield, Uzbekistan: the 1369 Sarycheku and Kalmakyr examples. International Geology Review, 60(1): 1-20. 1370 Chien, C.C. and Han, C.T., 2009. Tellurite Resistance and Reduction by a Paenibacillus Sp. 1371 Isolated from Heavy Metal‐Contaminated Sediment. Environmental toxicology and 1372 chemistry, 28(8): 1627-1632. 1373 Chivers, T. and Laitinen, R.S., 2015. Tellurium: a maverick among the chalcogens. Chemical 1374 Society Reviews, 44(7): 1725-1739. 1375 Choi, N.-C., Cho, K.H., Kim, B.J., Lee, S. and Park, C.Y., 2018. Enhancement of Au–Ag–Te 1376 contents in tellurium-bearing ore minerals via bioleaching. International Journal of 1377 Minerals, Metallurgy, and Materials, 25(3): 262-270. 1378 Choudhury, H.G., Cameron, A.D., Iwata, S. and Beis, K., 2011. Structure and mechanism of the 1379 chalcogen-detoxifying protein TehB from Escherichia coli. Biochemical Journal, 435(1): 1380 85-91. 1381 Chouinard, A., Paquette, J. and Williams-Jones, A.E., 2005. Crystallographic controls on trace- 1382 element incorporation in auriferous pyrite from the Pascua epithermal high- 1383 sulfidation deposit, Chile–Argentina. The Canadian Mineralogist, 43(3): 951-963. 1384 Christy, A.G., 2015. Causes of anomalous mineralogical diversity in the Periodic Table. 1385 Mineralogical Magazine, 79(1): 33-50. 1386 Christy, A.G., 2018. Quantifying lithophilicity, chalcophilicity and siderophilicity. European 1387 Journal of Mineralogy, 30(2): 193-204. 1388 Christy, A.G. and Mills, S.J., 2013. Effect of lone-pair stereoactivity on polyhedral volume and IV 1389 structural flexibility: application to Te O6 octahedra. Acta Crystallographica Section B, 1390 69(5): 446-456. 1391 Christy, A.G., Mills, S.J. and Kampf, A.R., 2016a. A review of the structural architecture of 1392 tellurium oxycompounds. Mineralogical Magazine, 80(3): 415-545. 1393 Christy, A.G., Mills, S.J., Kampf, A.R., Housley, R.M., Thorne, B. and Marty, J., 2016b. The 1394 relationship between mineral composition, crystal structure and paragenetic 1395 sequence: the case of secondary Te mineralization at the Bird Nest drift, Otto 1396 Mountain, California, USA. Mineralogical Magazine, 80(2): 291-310. 1397 Ciobanu, C.L., Cook, N.J., Damian, G.H., Damian, F. and Buia, G., 2004. Telluride and sulphosalt 1398 associations at Sacarimb. Au-Ag-Telluride Deposits of the Golden Quadrilateral, 1399 Apuseni Mts., Romania, 12: 145-186. 1400 Ciobanu, C.L., Cook, N.J. and Spry, P.G., 2006. Preface–Special Issue: Telluride and selenide 1401 minerals in gold deposits–how and why? Mineralogy and Petrology, 87(3-4): 163-169. 1402 Ciobanu, C.L., Cook, N.J., Pring, A., Brugger, J., Danyushevsky, L.V. and Shimizu, M., 2009. 1403 ‘Invisible gold’ in bismuth chalcogenides. Geochimica et Cosmochimica Acta, 73(7): 1404 1970-1999. 1405 Climo, M., Watling, H. and van Bronswijk, W., 2000a. Bio-oxidation of a Telluride-rich Gold 1406 Concentrate. Chemeca 2000: Opportunities and Challenges for the Resource and 1407 Processing Industries: 46. 1408 Climo, M., Watling, H.R. and Van Bronswijk, W., 2000b. Biooxidation as pre-treatment for a 1409 telluride-rich refractory gold concentrate. Minerals Engineering, 13(12): 1219-1229. 1410 Clout, J., Cleghorn, J. and Eaton, P., 1990. Geology of the Kalgoorlie gold field, Geology of the 1411 mineral deposits of Australia and Papua New Guinea. The Australasian Institute of 1412 Mining and Metallurgy, Melbourne, pp. 411-431. 1413 Cook, N.J., Ciobanu, C.L. and Mao, J., 2009a. Textural control on gold distribution in As-free 1414 pyrite from the Dongping, Huangtuliang and Hougou gold deposits, North China 1415 Craton (Hebei Province, China). Chemical Geology, 264(1-4): 101-121. 1416 Cook, N.J., Ciobanu, C.L., Pring, A., Skinner, W., Shimizu, M., Danyushevsky, L., Saini-Eidukat, 1417 B. and Melcher, F., 2009b. Trace and minor elements in sphalerite: A LA-ICPMS study. 1418 Geochimica et Cosmochimica Acta, 73(16): 4761-4791. 1419 Cook, N.J., Ciobanu, C.L., Spry, P.G. and Voudouris, P., 2009c. Understanding gold-(silver)- 1420 telluride-(selenide) mineral deposits. Episodes, 32(4): 249-263. 1421 Cooke, D.R. and McPhail, D., 2001. Epithermal Au-Ag-Te mineralization, Acupan, Baguio 1422 district, Philippines: numerical simulations of mineral deposition. Economic Geology, 1423 96(1): 109-131. 1424 Corper, H.J., 1915. Sodium Tellurite as a Rapid Test for the Viability of Tubercle Bacilli Studies 1425 on the Biochemistry and Chemotherapy of Tuberculosis, XIII. The Journal of Infectious 1426 Diseases: 47-53. 1427 Cowgill, U.M., 1988. The tellurium content of vegetation. Biological Trace Element Research, 1428 17(1): 43-67. 1429 Cunha, R.L., Gouvea, I.E. and Juliano, L., 2009. A glimpse on biological activities of tellurium 1430 compounds. Anais da Academia Brasileira de Ciências, 81(3): 393-407. 1431 Cyrs, W.D., Avens, H.J., Capshaw, Z.A., Kingsbury, R.A., Sahmel, J. and Tvermoes, B.E., 2014. 1432 Landfill waste and recycling: Use of a screening-level risk assessment tool for end-of- 1433 life cadmium telluride (CdTe) thin-film photovoltaic (PV) panels. Energy Policy, 68: 1434 524-533. 1435 Dare, S.A., Barnes, S.-J., Prichard, H.M. and Fisher, P.C., 2014. Mineralogy and geochemistry 1436 of Cu-rich ores from the McCreedy East Ni-Cu-PGE deposit (Sudbury, Canada): 1437 implications for the behavior of platinum group and chalcophile elements at the end 1438 of crystallization of a sulfide liquid. Economic Geology, 109(2): 343-366. 1439 De Ronde, C., Chadwick, W., Ditchburn, R., Embley, R., Tunnicliffe, V., Baker, E., Walker, S., 1440 Ferrini, V. and Merle, S., 2015. Molten sulfur lakes of intraoceanic arc volcanoes, 1441 Volcanic lakes. Springer, pp. 261-288. 1442 Deditius, A.P., Utsunomiya, S., Reich, M., Kesler, S.E., Ewing, R.C., Hough, R. and Walshe, J., 1443 2010. Trace-metal nanoparticles in pyrite. Ore Geology Reviews, 42: 32-46. 1444 Deditius, A.P., Reich, M., Kesler, S.E., Utsunomiya, S., Chryssoulis, S.L., Walshe, J. and Ewing, 1445 R.C., 2014. The coupled geochemistry of Au and As in pyrite from hydrothermal ore 1446 deposits. Geochimica et Cosmochimica Acta, 140: 644-670. 1447 Deen, J.A. and Atkinson Jr, W.W., 1988. Volcanic stratigraphy and ore deposits of the 1448 Moctezuma District, Sonora, Mexico. Economic Geology, 83(8): 1841-1855. 1449 Dhankhar, R. and Hooda, A., 2011. Fungal biosorption–an alternative to meet the challenges 1450 of heavy metal pollution in aqueous solutions. Environmental technology, 32(5): 467- 1451 491. 1452 Díaz-Vásquez, W.A., Abarca-Lagunas, M.J., Cornejo, F.A., Pinto, C.A., Arenas, F.A. and Vásquez, 1453 C.C., 2015. Tellurite-mediated damage to the Escherichia coli NDH-dehydrogenases 1454 and terminal oxidases in aerobic conditions. Archives of biochemistry and biophysics, 1455 566: 67-75. 1456 Dickson, R.S. and Glowa, G.A., 2019. Tellurium behaviour in the Fukushima Dai-ichi Nuclear 1457 Power Plant accident. Journal of environmental radioactivity, 204: 49-65. 1458 Dill, H.G., 2010. The “chessboard” classification scheme of mineral deposits: mineralogy and 1459 geology from aluminum to zirconium. Earth-Science Reviews, 100(1-4): 1-420. 1460 Dimpe, K.M. and Nomngongo, P.N., 2017. A review on the efficacy of the application of myriad 1461 carbonaceous materials for the removal of toxic trace elements in the environment. 1462 Trends in Environmental Analytical Chemistry, 16: 24-31. 1463 Ding, N., Chen, S.F., Geng, D.S., Chien, S.W., An, T., Hor, T.A., Liu, Z.L., Yu, S.H. and Zong, Y., 1464 2015. Tellurium@ Ordered Macroporous Carbon Composite and Free ‐ Standing 1465 Tellurium Nanowire Mat as Cathode Materials for Rechargeable Lithium–Tellurium 1466 Batteries. Advanced Energy Materials, 5(8): 1401999. 1467 Diso, D., Fauzi, F., Echendu, O., Olusola, O. and Dharmadasa, I., 2016. Optimisation of CdTe 1468 electrodeposition voltage for development of CdS/CdTe solar cells. Journal of 1469 Materials Science: Materials in Electronics, 27(12): 12464-12472. 1470 Dmitrijeva, M., Cook, N.J., Ehrig, K., Ciobanu, C.L., Metcalfe, A.V., Kamenetsky, M., 1471 Kamenetsky, V.S. and Gilbert, S., 2020. Multivariate Statistical Analysis of Trace 1472 Elements in Pyrite: Prediction, Bias and Artefacts in Defining Mineral Signatures. 1473 Minerals, 10(1): 61. 1474 Dodge, M.L, 2009. In: Tufa Towers of Mono Lake, Rove.me website, URL: 1475 https://rove.me/to/california/mono-lake-tufa-towers. 1476 Drozdovitch, V., Kryuchkov, V., Chumak, V., Kutsen, S., Golovanov, I. and Bouville, A., 2019. 1477 Thyroid doses due to Iodine-131 inhalation among Chernobyl cleanup workers. 1478 Radiation and environmental biophysics: 1-12. 1479 du Bray, E.A., 2017. Geochemical characteristics of igneous rocks associated with epithermal 1480 mineral deposits—a review. Ore Geology Reviews, 80: 767-783. 1481 Dunn, C.E., 2011. Biogeochemistry in mineral exploration. Vol. 9 of Handbook of Exploration 1482 and Environmental Chemistry. Elsevier Publishers, Amsterdam, The Netherlands. 1483 Ehrig, K., McPhie, J. and Kamenetsky, V., 2012. Geology and mineralogical zonation of the 1484 Olympic Dam iron oxide Cu-U-Au-Ag deposit, South Australia. 1485 Ehrlich, H. and Newman, D., 2009. Geomicrobiology CRC Press, Boca Raton, USA (606z pp.). 1486 Emsley, J., 2011. Nature's Building Blocks: an A-Z Guide to the Elements. Oxford University 1487 Press, Oxford. 1488 Endo, S., Fujii, K., Kajimoto, T., Tanaka, K., Stepanenko, V., Kolyzhenkov, T., Petukhov, A., 1489 Akhmedova, U. and Bogacheva, V., 2018. Comparison of calculated beta- and gamma- 1490 ray doses after the Fukushima accident with data from single-grain luminescence 1491 retrospective dosimetry of quartz inclusions in a brick sample. Journal of Radiation 1492 Research, 59(3): 286-290. 1493 Espinosa-Ortiz, E.J., Rene, E.R., Guyot, F., van Hullebusch, E.D. and Lens, P.N.L., 2017. 1494 Biomineralization of tellurium and selenium-tellurium nanoparticles by the white-rot 1495 fungus Phanerochaete chrysosporium. International Biodeterioration & 1496 Biodegradation, 124: 258-266. 1497 Estevam, E.C., Griffin, S., Nasim, M.J., Denezhkin, P., Schneider, R., Lilischkis, R., Dominguez- 1498 Alvarez, E., Witek, K., Latacz, G. and Keck, C., 2017. Natural selenium particles from 1499 Staphylococcus carnosus: Hazards or particles with particular promise? Journal of 1500 hazardous materials, 324: 22-30. 1501 Etezad, S.M., Khajeh, K., Soudi, M., Ghazvini, P.T.M. and Dabirmanesh, B., 2009. Evidence on 1502 the presence of two distinct enzymes responsible for the reduction of selenate and 1503 tellurite in Bacillus sp. STG-83. Enzyme and Microbial Technology, 45(1): 1-6. 1504 Etschmann, B.E., Liu, W., Pring, A., Grundler, P.V., Tooth, B., Borg, S., Testemale, D., Brewe, D. 1505 and Brugger, J., 2016. The role of Te(IV) and Bi(III) chloride complexes in hydrothermal 1506 mass transfer: an X-ray absorption spectroscopic study. Chemical Geology, 425: 37-51. 1507 Fairbrother, L., Shapter, J., Brugger, J., Southam, G., Pring, A. and Reith, F., 2009. Effect of the 1508 cyanide-producing bacterium Chromobacterium violaceum on ultraflat Au surfaces. 1509 Chemical Geology, 265(3): 313-320. 1510 Fairbrother, L., Brugger, J., Shapter, J., Laird, J., Southam, G. and Reith, F., 2012. Supergene 1511 gold transformation: Biogenic secondary and nano-particulate gold from arid Australia. 1512 Chemical Geology, 320: 17-31. 1513 Filella, M. and May, P.M., 2019. The aqueous chemistry of tellurium: critically-selected 1514 equilibrium constants for the low-molecular-weight inorganic species. Environmental 1515 Chemistry, 16(4): 289-295. 1516 Filella, M., Reimann, C., Biver, M., Rodushkin, I. and Rodushkina, K., 2019. Tellurium in the 1517 environment: current knowledge and identification of gaps. Environmental Chemistry, 1518 16(4): 215-228. 1519 Fleet, M.E. and Mumin, A.H., 1997. Gold-bearing arsenian pyrite and marcasite and 1520 arsenopyrite from Carlin Trend gold deposits and laboratory synthesis. American 1521 Mineralogist, 82(1-2): 182-193. 1522 Foreman, M.R.S.J., 2015. An introduction to serious nuclear accident chemistry. Cogent 1523 Chemistry, 1(1): 1049111. 1524 Frishberg, M., 2017. Advances in Solar Power Light the Future. Research Technology 1525 Management, 60(2): 7. 1526 Frost, B.R., Mavrogenes, J.A. and Tomkins, A.G., 2002. Partial melting of sulfide ore deposits 1527 during medium-and high-grade metamorphism. The Canadian Mineralogist, 40(1): 1- 1528 18. 1529 Fthenakis, V. and Wang, W., 2006. Extraction and separation of Cd and Te from cadmium 1530 telluride photovoltaic manufacturing scrap. Progress in Photovoltaics: Research and 1531 Applications, 14(4): 363-371. 1532 Fulignati, P. and Sbrana, A., 1998. Presence of native gold and tellurium in the active high- 1533 sulfidation hydrothermal system of the La Fossa volcano (Vulcano, Italy). Journal of 1534 Volcanology and Geothermal Research, 86(1-4): 187-198. 1535 Gao, S., Xu, H., Li, S., Santosh, M., Zhang, D., Yang, L. and Quan, S., 2017. Hydrothermal 1536 alteration and ore-forming fluids associated with gold-tellurium mineralization in the 1537 Dongping gold deposit, China. Ore Geology Reviews, 80: 166-184. 1538 Gavrilescu, M., 2004. Removal of heavy metals from the environment by biosorption. 1539 Engineering in Life Sciences, 4(3): 219-232. 1540 Genkin, A. and Evstigneeva, T., 1986. Associations of platinum-group minerals of the Noril'sk 1541 copper-nickel sulfide ores. Economic Geology, 81(5): 1203-1212. 1542 George, L.L., Cook, N.J., Crowe, B.B. and Ciobanu, C.L., 2018. Trace Elements in Hydrothermal 1543 Chalcopyrite. Mineralogical Magazine, 82(1): 59-88. 1544 Gerhardsson, L., 2015. Tellurium, Handbook on the Toxicology of Metals. Elsevier, pp. 1217- 1545 1228. 1546 Gharieb, M.M., Kierans, M. and Gadd, G.M., 1999. Transformation and tolerance of tellurite 1547 by filamentous fungi: accumulation, reduction, and volatilization. Mycological 1548 Research, 103(3): 299-305. 1549 Gil-Díaz, T., 2019. Tellurium radionuclides produced by major accidental events in nuclear 1550 power plants. Environmental Chemistry, 16(4): 296–302. 1551 Gil-Díaz, T., Schäfer, J., Dutruch, L., Bossy, C., Pougnet, F., Abdou, M., Lerat-Hardy, A., Pereto, 1552 C., Derriennic, H. and Briant, N., 2019a. Tellurium behaviour in a major European 1553 fluvial–estuarine system (Gironde, France): fluxes, solid/liquid partitioning and 1554 bioaccumulation in wild oysters. Environmental Chemistry, 16(4): 229–242. 1555 Gil-Díaz, T., Schäfer, J., Dutruch, L. and Eyrolle-Boyer, F., 2019b. Tellurium radionuclide 1556 dispersion scenarios in aquatic systems: coupling of adsorption kinetics, radionuclide 1557 decay and estuarine hydrodynamics. Book of Abstracts of the Advanced Workshop on 1558 Solution Chemistry of TCEs (Technology Critical Elements), Bialystok, pp. 26. 1559 Goff, J. and Yee, N., 2017. Tellurate enters Escherichia coli K-12 cells via the SulT-type sulfate 1560 transporter CysPUWA. FEMS microbiology letters, 364(24): fnx241. 1561 Goldfarb, R.J., 2014. Tellurium: The Bright Future of Solar Energy. US Department of the 1562 Interior, US Geological Survey. 1563 Goldfarb, R.J., Berger, B.R., George, M.W., and Seal, R.R., II, 2017, Tellurium, chap. R of Schulz, 1564 K.J., DeYoung, J.H., Jr., Seal, R.R., II, and Bradley, D.C., eds., Critical mineral resources 1565 of the United States—Economic and environmental geology and prospects for future 1566 supply: U.S. Geological Survey Professional Paper 1802, p. R1–R27, DOI: 1567 10.3133/pp1802R. 1568 Gott, G.B. and McCarthy, J.H.J., 1966. Distribution of gold, silver, tellurium, and mercury in 1569 the Ely mining district, White Pine County, Nevada. In: U.S.Dept of the Interior (Editor), 1570 pp. 5 p. 1571 Green, M.A., 2011. Is sour crude or sour gas a potential source of Se and Te? Progress in 1572 Photovoltaics: Research and Applications, 19(8): 991-995. 1573 Greenland, L.P. and Aruscavage, P., 1986. Volcanic emission of Se, Te, and As from Kilauea 1574 volcano, Hawaii. Journal of Volcanology and Geothermal Research, 27(1): 195-201. 1575 Grundler, P.V., Brugger, J., Etschmann, B.E., Helm, L., Liu, W., Spry, P.G., Tian, Y., Testemale, 1576 D. and Pring, A., 2013. Speciation of aqueous tellurium (IV) in hydrothermal solutions 1577 and vapors, and the role of oxidized tellurium species in Te transport and gold 1578 deposition. Geochimica et Cosmochimica Acta, 120: 298-325. 1579 Guo, Y.F., Deng, T.L., Zhang, N. and Liao, M.X., 2012a. Tellurium Extraction from the Unique 1580 Independent Tellurium Ores in China by Bioleaching, Advanced Materials Research. 1581 Trans Tech Publ, pp. 625-630. 1582 Guo, Y.F., Zhang, N., Li, D.C., Tang, F.M. and Deng, T.L., 2012b. Tellurium recovery from the 1583 unique tellurium ores, Advanced Materials Research. Trans Tech Publ, pp. 1060-1063. 1584 Hardardóttir, V., Brown, K., Fridriksson, T., Hedenquist, J., Hannington, M. and Thorhallsson, 1585 S., 2009. Metals in deep liquid of the Reykjanes geothermal system, southwest Iceland: 1586 Implications for the composition of seafloor black smoker fluids. Geology, 37(12): 1587 1103-1106. 1588 Hattori, K.H., Arai, S. and Clarke, D.B., 2002. Selenium, tellurium, arsenic and antimony 1589 contents of primary mantle sulfides. The Canadian Mineralogist, 40(2): 637-650. 1590 Hayes, S.M. and Ramos, N.A., 2019. Surficial geochemistry and bioaccessibility of tellurium in 1591 semiarid mine tailings. Environmental Chemistry, 16(4): 251-265. 1592 He, J., Chen, Y., Lv, W., Wen, K., Wang, Z., Zhang, W., Li, Y., Qin, W. and He, W., 2016. Three- 1593 dimensional hierarchical reduced graphene oxide/tellurium nanowires: a high- 1594 performance freestanding cathode for Li–Te batteries. ACS nano, 10(9): 8837-8842. 1595 He, J., Lv, W., Chen, Y., Wen, K., Xu, C., Zhang, W., Li, Y., Qin, W. and He, W., 2017. Tellurium- 1596 impregnated porous cobalt-doped carbon polyhedra as superior cathodes for lithium– 1597 tellurium batteries. ACS nano, 11(8): 8144-8152. 1598 Hein, J.R., Koschinsky, A. and Halliday, A.N., 2003. Global occurrence of tellurium-rich 1599 ferromanganese crusts and a model for the enrichment of tellurium. Geochimica et 1600 Cosmochimica Acta, 67(6): 1117-1127. 1601 Heitt, D.G., Dunbar, W.W., Thompson, T.B. and Jackson, R.G., 2003. Geology and 1602 geochemistry of the Deep Star gold deposit, Carlin trend, Nevada. Economic Geology, 1603 98(6): 1107-1135. 1604 Helmy, H.M., Ballhaus, C., Berndt, J., Bockrath, C. and Wohlgemuth-Ueberwasser, C., 2007. 1605 Formation of Pt, Pd and Ni tellurides: experiments in sulfide–telluride systems. 1606 Contributions to Mineralogy and Petrology, 153(5): 577-591. 1607 Hitzman, M.W., Reynolds, N.A., Sangster, D., Allen, C.R. and Carman, C.E., 2003. Classification, 1608 genesis, and exploration guides for nonsulfide zinc deposits. Economic Geology, 98(4): 1609 685-714. 1610 Holwell, D.A., Adeyemi, Z., Ward, L.A., Smith, D.J., Graham, S.D., McDonald, I. and Smith, J.W., 1611 2017. Low temperature alteration of magmatic Ni-Cu-PGE sulfides as a source for 1612 hydrothermal Ni and PGE ores: A quantitative approach using automated mineralogy. 1613 Ore Geology Reviews, 91: 718-740. 1614 Holwell, D.A., Fiorentini, M., McDonald, I., Lu, Y., Giuliani, A., Smith, D.J., Keith, M. and 1615 Locmelis, M., 2019. A metasomatized lithospheric mantle control on the metallogenic 1616 signature of post-subduction magmatism. Nature Communications, 10(1): 3511. 1617 Hu, Z. and Gao, S., 2008. Upper crustal abundances of trace elements: a revision and update. 1618 Chemical Geology, 253(3-4): 205-221. 1619 Jacobson, M., W. Keller, J. and W. Atkinson Jr, W., 2018. The Where of Mineral Names: 1620 Moctezumite, Moctezuma Mine (La Bambolla Mine), Moctezuma, Municipality of 1621 Moctezuma, State of Sonora, Mexico. Rocks & Minerals, 93(5): 466-471. 1622 Jain, R., Gonzalez-Gil, G., Singh, V., Van Hullebusch, E.D., Farges, F. and Lens, P.N.L., 2014. 1623 Biogenic selenium nanoparticles: production, characterization and challenges. 1624 Nanobiotechnology, Studium Press LLC, USA: 361-390. 1625 Jain, R., Matassa, S., Singh, S., van Hullebusch, E.D., Esposito, G. and Lens, P.N., 2016. 1626 Reduction of selenite to elemental selenium nanoparticles by activated sludge. 1627 Environmental Science and Pollution Research, 23(2): 1193-1202. 1628 Kagami, T., Fudemoto, A., Fujimoto, N., Notaguchi, E., Kanzaki, M., Kuroda, M., Soda, S., 1629 Yamashita, M. and Ike, M., 2012. Isolation and characterization of bacteria capable of 1630 reducing tellurium oxyanions to insoluble elemental tellurium for tellurium recovery 1631 from wastewater. Waste and Biomass Valorization, 3(4): 409-418. 1632 Kagoshima, T., Sano, Y., Takahata, N., Maruoka, T., Fischer, T.P. and Hattori, K., 2015. Sulphur 1633 geodynamic cycle. Scientific reports, 5: 8330. 1634 Kampf, A.R., Cooper, M.A., Mills, S.J., Housley, R.M. and Rossman, G.R., 2016. Lead-tellurium 1635 oxysalts from Otto Mountain near Baker, California, USA: XII. Andychristyite, 2+ 6+ 1636 PbCu Te O5(H2O), a new mineral with hcp stair-step layers. Mineralogical Magazine, 1637 80(6): 1055-1065. 1638 Kanai, Y., 2015. Geochemical behavior and activity ratios of Fukushima-derived radionuclides 1639 in aerosols at the Geological Survey of Japan, Tsukuba, Japan. Journal of 1640 Radioanalytical and Nuclear Chemistry, 303(2): 1405-1408. 1641 Kavlak, G. and Graedel, T., 2013. Global anthropogenic tellurium cycles for 1940–2010. 1642 Resources, Conservation and Recycling, 76: 21-26. 1643 Keith, M., Smith, D.J., Jenkin, G.R.T., Holwell, D.A. and Dye, M.D., 2018. A review of Te and Se 1644 systematics in hydrothermal pyrite from precious metal deposits: Insights into ore- 1645 forming processes. Ore Geology Reviews, 96: 269-282. 1646 Kelley, K.D., Romberger, S.B., Beaty, D.W., Pontius, J.A., Snee, L.W., Stein, H.J. and Thompson, 1647 T.B., 1998. Geochemical and geochronological constraints on the genesis of Au-Te 1648 deposits at Cripple Creek, Colorado. Economic Geology, 93(7): 981-1012. 1649 Kesler, S.E. and Wilkinson, B.H., 2008. Earth's copper resources estimated from tectonic 1650 diffusion of porphyry copper deposits. Geology, 36(3): 255-258. 1651 Khaing, S.Y., Sugai, Y. and Sasaki, K., 2019. Gold Dissolution from Ore with Iodide-Oxidising 1652 Bacteria. Scientific Reports, 9(1): 4178. 1653 Kim, D.-H., Kanaly, R.A. and Hur, H.-G., 2012a. Biological accumulation of tellurium nanorod 1654 structures via reduction of tellurite by Shewanella oneidensis MR-1. Bioresource 1655 Technology, 125: 127-131. 1656 Kim, E.-J., Park, M.-E. and White, N.C., 2012b. Skarn gold mineralization at the Geodo mine, 1657 South Korea. Economic Geology, 107(3): 537-551. 1658 Kim, P., Kim, H., Myung, E., Kim, Y. and Lee, Y., 2015. The enhancing of Au-Ag-Te content in 1659 tellurium-bearing ore mineral by bio-oxidation-leaching, EGU General Assembly 1660 Conference Abstracts. 1661 King, J., Williams-Jones, A., van Hinsberg, V. and Williams-Jones, G., 2014. High-sulfidation 1662 epithermal pyrite-hosted Au (Ag-Cu) ore formation by condensed magmatic vapors on 1663 Sangihe Island, Indonesia. Economic Geology, 109(6): 1705-1733. 1664 King, W.E. and Davis, L., 1914. Potassium tellurite as an indicator of microbial life. American 1665 Journal of Public Health, 4(10): 917-932. 1666 Kingston, G.A., 1966. The occurrence of platinoid bismuthotellurides in the Merensky Reef at 1667 Rustenburg platinum mine in the western Bushveld. Mineralogical Magazine, 35(274): 1668 815-834. 1669 Klaproth, M.H., 1798. XVIII. Extract from a memoir on a new metal called tellurium. The 1670 Philosophical Magazine, 1(1): 78-82. 1671 Klonowska, A., Heulin, T. and Vermeglio, A., 2005. Selenite and tellurite reduction by 1672 Shewanella oneidensis. Applied and environmental microbiology, 71(9): 5607-5609. 1673 Knockaert, G., 2011. Tellurium and tellurium compounds. In ‘Ullmann’s encyclopedia of 1674 industrial chemistry’. Wiley‐VCH Verlag GmbH & Co. KGaA: Weinheim. 1675 Konstantinov, M. and Grushin, V., 1970. Geologic position of the Zod-Agduzdag gold-ore node 1676 in Transcaucasia. International Geology Review, 12(12): 1447-1453. 1677 Kumar, M. and Kumar, S., 2015. Luminescent CdTe quantum dots incarcerated in a columnar 1678 matrix of discotic liquid crystals for optoelectronic applications. RSC Advances, 5(2): 1679 1262-1267. 1680 Kyle, J., Breuer, P., Bunney, K., Pleysier, R. and May, P., 2011. Review of trace toxic elements 1681 (Pb, Cd, Hg, As, Sb, Bi, Se, Te) and their deportment in gold processing. Part 1: 1682 Mineralogy, aqueous chemistry and toxicity. Hydrometallurgy, 107(3-4): 91-100. 1683 LeFort, D., Hanley, J. and Guillong, M., 2011. Subepithermal Au-Pd Mineralization Associated 1684 with an Alkalic Porphyry Cu-Au Deposit, Mount Milligan, Quesnel Terrane, British 1685 Columbia, Canada. Economic Geology, 106(5): 781-808. 1686 Li, L., Daou, T.J., Texier, I., Kim Chi, T.T., Liem, N.Q. and Reiss, P., 2009. Highly luminescent 1687 CuInS2/ZnS core/shell nanocrystals: cadmium-free quantum dots for in vivo imaging. 1688 Chemistry of Materials, 21(12): 2422-2429. 1689 Liang, X., Perez, M.A.M.-J., Nwoko, K.C., Egbers, P., Feldmann, J., Csetenyi, L. and Gadd, G.M., 1690 2019. Fungal formation of selenium and tellurium nanoparticles. Applied microbiology 1691 and biotechnology, 103(17): 7241-7259. 1692 Lin, S., Li, W., Chen, Z., Shen, J., Ge, B. and Pei, Y., 2016. Tellurium as a high-performance 1693 elemental thermoelectric. Nature communications, 7: 10287. 1694 Liu, J.-W., Zhu, J.-H., Zhang, C.-L., Liang, H.-W. and Yu, S.-H., 2010. Mesostructured assemblies 1695 of ultrathin superlong tellurium nanowires and their photoconductivity. Journal of the 1696 American Chemical Society, 132(26): 8945-8952. 1697 Lodders, K., 2010. Solar system abundances of the elements, Principles and perspectives in 1698 cosmochemistry. Springer, pp. 379-417. 1699 Lovrić, J., Cho, S.J., Winnik, F.M. and Maysinger, D., 2005. Unmodified cadmium telluride 1700 quantum dots induce reactive oxygen species formation leading to multiple organelle 1701 damage and cell death. Chemistry & biology, 12(11): 1227-1234. 1702 Mahdavi, S., Khanmohammadi, H. and Masteri-Farahani, M., 2018. Surface functionalized 1703 cadmium telluride quantum dots for the optical detection and determination of 1704 herbicides. Journal of Materials Science: Materials in Electronics: 1-6. 1705 Makuei, F.M. and Senanayake, G., 2018. Extraction of tellurium from lead and copper bearing 1706 feed materials and interim metallurgical products–A short review. Minerals 1707 Engineering, 115: 79-87. 1708 Mal, J., Nancharaiah, Y.V., Maheshwari, N., van Hullebusch, E.D. and Lens, P.N.L., 2017. 1709 Continuous removal and recovery of tellurium in an upflow anaerobic granular sludge 1710 bed reactor. Journal of Hazardous Materials, 327: 79-88. 1711 Maltman, C., Walter, G. and Yurkov, V., 2016. A diverse community of metal (loid) oxide 1712 respiring bacteria is associated with tube worms in the vicinity of the Juan de Fuca 1713 Ridge black smoker field. PloS one, 11(2): e0149812. 1714 Maltman, C., Donald, L.J. and Yurkov, V., 2017. Two distinct periplasmic enzymes are 1715 responsible for tellurite/tellurate and selenite reduction by strain ER-Te-48 associated 1716 with the deep sea hydrothermal vent tube worms at the Juan de Fuca Ridge black 1717 smokers. Archives of microbiology, 199(8): 1113-1120. 1718 Manikandan, M., Dhanuskodi, S., Maheswari, N., Muralidharan, G., Revathi, C., Kumar, R.R. 1719 and Rao, G.M., 2017. High performance supercapacitor and non-enzymatic hydrogen 1720 peroxide sensor based on tellurium nanoparticles. Sensing and Bio-Sensing Research, 1721 13: 40-48. 1722 Mao, J., Wang, Y., Ding, T., CHEN, Y., WEI, J. and YIN, J., 2002. Dashuigou tellurium deposit in 1723 Sichuan Province, China: S, C, O, and H isotope data and their implications on 1724 hydrothermal mineralization. Resource Geology, 52(1): 15-23. 1725 Marwede, M. and Reller, A., 2012. Future recycling flows of tellurium from cadmium telluride 1726 photovoltaic waste. Resources, Conservation and Recycling, 69: 35-49. 1727 Maslennikov, V., Maslennikova, S., Large, R., Danyushevsky, L., Herrington, R. and Stanley, C., 1728 2013. Tellurium-bearing minerals in zoned sulfide chimneys from Cu-Zn massive 1729 sulfide deposits of the Urals, Russia. Mineralogy and Petrology, 107(1): 67-99. 1730 McDonough, W.F. and Sun, S.-S., 1995. The composition of the Earth. Chemical geology, 1731 120(3-4): 223-253. 1732 McFall, K.A., Naden, J., Roberts, S., Baker, T., Spratt, J. and McDonald, I., 2018. Platinum-group 1733 minerals in the Skouries Cu-Au (Pd, Pt, Te) porphyry deposit. Ore Geology Reviews, 99: 1734 344-364. 1735 McPhail, D.C., 1995. Thermodynamic properties of aqueous tellurium species between 25 and 1736 350ºC. Geochimica et Cosmochimica Acta, 59(5): 851-866. 1737 Mehrabi, B., Yardley, B. and Cann, J., 1999. Sediment-hosted disseminated gold 1738 mineralisation at Zarshuran, NW Iran. Mineralium Deposita, 34(7): 673-696. 1739 Meintjes, T., Bob, L., Gary, G. and Marc, S., 2018. NI-43-101 Technical report on the 1740 preliminary economic assessment for the Deer Horn gold-silver-tellurium property. 1741 Mills, K.C., 1974. Thermodynamic data for inorganic sulphides, selenides and tellurides. 1742 Mills, S.J. and Christy, A.G., 2013. Revised values of the bond-valence parameters for TeIV-O, 1743 TeVI-O and TeIV-Cl. Acta Crystallographica Section B, 69(2): 145-149. 1744 Mills, S.J. and Christy, A.G., 2019. Mineral extinction. Mineralogical Magazine, 83(5): 621-625. 1745 Missen, O.P., Kampf, A.R., Mills, S.J., Housley, R.M., Spratt, J., Welch, M.D., Coolbaugh, M.F., 1746 Marty, J., Chorazewicz, M. and Ferraris, C., 2019. The crystal structures of the mixed- 4+ 6+ 4+ 1747 valence tellurium oxysalts tlapallite, (Ca,Pb)3CaCu6[Te 3Te O12]2(Te O3)2(SO4)2·3H2O, 4+ 6+ 1748 and carlfriesite, CaTe 2Te O8. Mineralogical Magazine, 83(4): 539-549. 1749 Moëlo, Y., Makovicky, E., Mozgova, N.N., Jambor, J.L., Cook, N., Pring, A., Paar, W., Nickel, 1750 E.H., Graeser, S. and Karup-Møller, S., 2008. Sulfosalt systematics: a review. Report of 1751 the sulfosalt sub-committee of the IMA Commission on Ore Mineralogy. European 1752 Journal of Mineralogy, 20(1): 7-46. 1753 Mueller, A.G., Hagemann, S.G., Brugger, J., Xing, Y. and Roberts, M.P., 2020. Early Fimiston 1754 pyrite and late Oroya pyrite-telluride gold ore, Paringa, South mine, Golden Mile, 1755 Kalgoorlie: 4. Mineralogy and PTX constraints on superimposed magmatic- 1756 hydrothermal systems. Mineralium Deposita. Invited paper under review since May 29 1757 2019. 1758 Murray, C.B., Norris, D.J. and Bawendi, M.G., 1993. Synthesis and characterization of nearly 1759 monodisperse CdE (E = sulfur, selenium, tellurium) semiconductor nanocrystallites. 1760 Journal of the American Chemical Society, 115(19): 8706-8715. 1761 Nancharaiah, Y.V. and Lens, P., 2015. Ecology and biotechnology of selenium-respiring 1762 bacteria. Microbiology and Molecular Biology Reviews, 79(1): 61-80. 1763 Nancharaiah, Y.V., Mohan, S.V. and Lens, P., 2016. Biological and bioelectrochemical recovery 1764 of critical and scarce metals. Trends in biotechnology, 34(2): 137-155. 1765 Norman, M., 2017. Copper tellurium oxides–A playground for magnetism. Journal of 1766 Magnetism and Magnetic Materials. 1767 Nuss, P., 2019. Losses and environmental aspects of a byproduct metal: tellurium. 1768 Environmental Chemistry, 16(4): 243-250. 1769 O'Neill, H.S.C. and Palme, H., 2008. Collisional erosion and the non-chondritic composition of 1770 the terrestrial planets. Philosophical Transactions of the Royal Society A: 1771 Mathematical, Physical and Engineering Sciences, 366(1883): 4205-4238. 1772 Ogra, Y., 2009. Toxicometallomics for research on the toxicology of exotic metalloids based 1773 on speciation studies. Analytical Sciences, 25(10): 1189-1195. 1774 Ogra, Y., 2017. Biology and toxicology of tellurium explored by speciation analysis. 1775 Metallomics, 9(5): 435-441. 1776 Okrugin, V.M., Andreeva, E., Etschmann, B., Pring, A., Li, K., Zhao, J., Griffiths, G., Lumpkin, 1777 G.R., Triani, G. and Brugger, J., 2014. Microporous gold: Comparison of textures from 1778 Nature and experiments. American Mineralogist, 99: 1171-1174. 1779 Okrugin, V.M., Favero, M., Liu, A., Etschmann, B., Plutachina, E., Mills, S., Tomkins, A.G., 1780 Lukasheva, M., Kozlov, V., Moskaleva, S., Chubarov, M. and Brugger, J., 2017. Smoking 1781 gun for thallium geochemistry in volcanic arcs: Nataliyamalikite, TlI, a new thallium 1782 mineral from an active fumarole at Avacha Volcano, Kamchatka Peninsula, Russia. 1783 American Mineralogist, 102(8): 1736-1746. 1784 Olivotos, S. and Economou-Eliopoulos, M., 2016. Gibbs free energy of formation for selected 1785 platinum group minerals (PGM). Geosciences, 6(1): 2. 1786 Ollivier, P.R., Bahrou, A.S., Marcus, S., Cox, T., Church, T.M. and Hanson, T.E., 2008. 1787 Volatilization and precipitation of tellurium by aerobic, tellurite-resistant marine 1788 microbes. Applied and environmental microbiology, 74(23): 7163-7173. 1789 Ottosson, L.-G., Logg, K., Ibstedt, S., Sunnerhagen, P., Käll, M., Blomberg, A. and Warringer, J., 1790 2010. Sulfate assimilation mediates tellurite reduction and toxicity in Saccharomyces 1791 cerevisiae. Eukaryotic cell, 9(10): 1635-1647. 1792 Pages, D., Rose, J., Conrod, S., Cuine, S., Carrier, P., Heulin, T. and Achouak, W., 2011. Heavy 1793 Metal Tolerance in Stenotrophomonas maltophilia, Environmental Chemistry. Apple 1794 Academic Press, pp. 128-136. 1795 Pals, D.W. and Spry, P., 2003. Telluride mineralogy of the low-sulfidation epithermal Emperor 1796 gold deposit, Vatukoula, Fiji. Mineralogy and Petrology, 79(3-4): 285-307. 1797 Pals, D.W., Spry, P.G. and Chryssoulis, S., 2003. Invisible gold and tellurium in arsenic-rich 1798 pyrite from the Emperor gold deposit, Fiji: implications for gold distribution and 1799 deposition. Economic Geology, 98(3): 479-493. 1800 Parnell, J., Bellis, D., Feldmann, J. and Bata, T., 2015. Selenium and tellurium enrichment in 1801 palaeo-oil reservoirs. Journal of Geochemical Exploration, 148: 169-173. 1802 Parnell, J., Spinks, S. and Bellis, D., 2016. Low‐temperature concentration of tellurium and 1803 gold in continental red bed successions. Terra Nova, 28(3): 221-227. 1804 Parnell, J., Spinks, S. and Brolly, C., 2018. Tellurium and selenium in Mesoproterozoic red beds. 1805 Precambrian Research, 305: 145-150. 1806 Pasero, M., 2019. The New IMA List of Minerals, available via http://cnmnc.main.jp/. 1807 Perkins, W.T., 2011. Extreme selenium and tellurium contamination in soils—An eighty year- 1808 old industrial legacy surrounding a Ni refinery in the Swansea Valley. Science of the 1809 Total Environment, 412: 162-169. 1810 Pi , J., Yang, F., Jin, H., Huang, X., Liu, R. and Yang, P., 2013. Selenium nanoparticles induced 1811 membrane biomechanical property changes in MCF-7 cells by disturbing membrane 1812 molecules and F-actin. Bioorg.Med.Chem.Lett., 23: 6296–6303. 1813 Piacenza, E., Presentato, A., Zonaro, E., Lampis, S., Vallini, G. and Turner, R.J., 2017. Microbial- 1814 based bioremediation of selenium and tellurium compounds, Biosorption. IntechOpen. 1815 Pinel-Raffaitin, P., Pécheyran, C. and Amouroux, D., 2008. New volatile selenium and tellurium 1816 species in fermentation gases produced by composting duck manure. Atmospheric 1817 Environment, 42(33): 7786-7794. 1818 Pons, T., Pic, E., Lequeux, N., Cassette, E., Bezdetnaya, L., Guillemin, F., Marchal, F. and 1819 Dubertret, B., 2010. Cadmium-free CuInS2/ZnS quantum dots for sentinel lymph node 1820 imaging with reduced toxicity. ACS nano, 4(5): 2531-2538. 1821 Presentato, A., Piacenza, E., Anikovskiy, M., Cappelletti, M., Zannoni, D. and Turner, R.J., 2016. 1822 Rhodococcus aetherivorans BCP1 as cell factory for the production of intracellular 1823 tellurium nanorods under aerobic conditions. Microbial cell factories, 15(1): 204. 1824 Presentato, A., Turner, R.J., Vásquez, C.C., Yurkov, V. and Zannoni, D., 2019. Tellurite- 1825 dependent blackening of bacteria emerges from the dark ages. Environmental 1826 Chemistry, 16(4): 266-288. 1827 Pudack, C., Halter, W., Heinrich, C.A. and Pettke, T., 2009. Evolution of magmatic vapor to 1828 gold-rich epithermal liquid: The porphyry to epithermal transition at Nevados de 1829 Famatina, northwest Argentina. Economic Geology, 104(4): 449-477. 1830 Qin, H.-B., Takeichi, Y., Nitani, H., Terada, Y. and Takahashi, Y., 2017. Tellurium distribution 1831 and speciation in contaminated soils from abandoned mine tailings: comparison with 1832 selenium. Environmental science & technology, 51(11): 6027-6035. 1833 Rajwade, J. and Paknikar, K., 2003. Bioreduction of tellurite to elemental tellurium by 1834 Pseudomonas mendocina MCM B-180 and its practical application. Hydrometallurgy, 1835 71(1-2): 243-248. 1836 Ram, R., Vaughan, J., Etschmann, B. and Brugger, J., 2019. The aqueous chemistry of polonium 1837 (Po) in environmental and anthropogenic processes. Journal of Hazardous Materials, 1838 380: 120725. 1839 Ramadan, S.E., Razak, A.A., Ragab, A.M. and El-Meleigy, M., 1989. Incorporation of tellurium 1840 into amino acids and proteins in a tellurium-tolerant fungi. Biological Trace Element 1841 Research, 20(3): 225. 1842 Ramos-Ruiz, A., Field, J.A., Wilkening, J.V. and Sierra-Alvarez, R., 2016. Recovery of elemental 1843 tellurium nanoparticles by the reduction of tellurium oxyanions in a methanogenic 1844 microbial consortium. Environmental science & technology, 50(3): 1492-1500. 1845 Ramos-Ruiz, A., Sesma-Martin, J., Sierra-Alvarez, R. and Field, J.A., 2017a. Continuous 1846 reduction of tellurite to recoverable tellurium nanoparticles using an upflow 1847 anaerobic sludge bed (UASB) reactor. Water Research, 108: 189-196. 1848 Ramos-Ruiz, A., Wilkening, J.V., Field, J.A. and Sierra-Alvarez, R., 2017b. Leaching of cadmium 1849 and tellurium from cadmium telluride (CdTe) thin-film solar panels under simulated 1850 landfill conditions. Journal of hazardous materials, 336: 57-64. 1851 Ray, G.E., Dawson, G.L. and Simpson, R., 1987. The Geology and Controls of Skarn 1852 Mineralization in the Hedley Gold Camp Southem British Columbia* (92W8, 82315), 1853 Geological Fieldwork. BC Ministry of Energy, Mines and Petroleum Resources. 1854 Rea, M.A., Zammit, C.M. and Reith, F., 2016. Bacterial biofilms on gold grains—implications 1855 for geomicrobial transformations of gold. FEMS Microbiology Ecology, 92(6): fiw082- 1856 fiw082. 1857 Rea, M.A.D., Wulser, P.-A., Brugger, J., Etschmann, B., Bissett, A., Shuster, J. and Reith, F., 1858 2018. Effect of physical and biogeochemical factors on placer gold transformation in 1859 mountainous landscapes of Switzerland. Gondwana Research. 1860 Reese, M.O., Glynn, S., Kempe, M.D., McGott, D.L., Dabney, M.S., Barnes, T.M., Booth, S., 1861 Feldman, D. and Haegel, N.M., 2018. Increasing markets and decreasing package 1862 weight for high-specific-power photovoltaics. Nature Energy, 3(11): 1002. 1863 Reith, F., Lengke, M.F., Falconer, D., Craw, D. and Southam, G., 2007. The geomicrobiology of 1864 gold. The ISME Journal, 1(7): 567-584. 1865 Reith, F., Etschmann, B., Grosse, C., Moors, H., Benotmane, M.A., Monsieurs, P., Grass, G., 1866 Doonan, C., Vogt, S., Lai, B., Martinez-Criado, G., George, G.N., Nies, D.H., Mergeay, 1867 M., Pring, A., Southam, G. and Brugger, J., 2009. Mechanisms of gold biomineralization 1868 in the bacterium Cupriavidus metallidurans. Proceedings of the National Academy of 1869 Sciences, 106(42): 17757-17762. 1870 Reith, F., Brugger, J., Zammit, C.M., Nies, D.H. and Southam, G., 2013. Geobiological cycling 1871 of gold: from fundamental process understanding to exploration solutions. Minerals, 1872 3(4): 367-394. 1873 Reith, F., Campbell, S., Ball, A., Pring, A. and Southam, G., 2014. Platinum in Earth surface 1874 environments. Earth-Science Reviews, 131: 1-21. 1875 Reith, F., Zammit, C.M., Shar, S.S., Etschmann, B., Bottrill, R., Southam, G., Ta, C., Kilburn, M., 1876 Oberthür, T. and Ball, A.S., 2016. Biological role in the transformation of platinum- 1877 group mineral grains. Nature Geoscience, 9(4): 294-298. 1878 Reith, F., Nolze, G., Saliwan-Neumann, R., Etschmann, B., Kilburn, M.R. and Brugger, J., 2019. 1879 Unravelling the formation histories of placer gold and platinum-group mineral 1880 particles from Corrego Bom Successo, Brazil: A window into noble metal cycling. 1881 Gondwana Research. 1882 Roberts, S., Palmer, M.R. and Waller, L., 2006. Sm-Nd and REE characteristics of tourmaline 1883 and scheelite from the Bjorkdal gold deposit, northern Sweden: Evidence of an 1884 intrusion-related gold deposit? Economic Geology, 101(7): 1415-1425. 1885 Rollog, M., Cook, N.J., Guagliardo, P., Ehrig, K., Ciobanu, C.L. and Kilburn, M., 2019. Detection 1886 of Trace Elements/Isotopes in Olympic Dam Copper Concentrates by nanoSIMS. 1887 Minerals, 9(6): 336. 1888 Rose-Weston, L., Brenan, J.M., Fei, Y., Secco, R.A. and Frost, D.J., 2009. Effect of pressure, 1889 temperature, and oxygen fugacity on the metal-silicate partitioning of Te, Se, and S: 1890 Implications for earth differentiation. Geochimica et Cosmochimica Acta, 73(15): 1891 4598-4615. 1892 Ruck, M. and Locherer, F., 2015. Coordination chemistry of homoatomic ligands of bismuth, 1893 selenium and tellurium. Coordination Chemistry Reviews, 285: 1-10. 1894 Sanyal, S.K., Shuster, J. and Reith, F., 2019. Cycling of biogenic elements drives biogeochemical 1895 gold cycling. Earth-Science Reviews, 190: 131-147. 1896 Sen, S., Sharma, M., Kumar, V., Muthe, K., Satyam, P., Bhatta, U.M., Roy, M., Gaur, N., Gupta, 1897 S. and Yakhmi, J., 2009. Chlorine gas sensors using one-dimensional tellurium 1898 nanostructures. Talanta, 77(5): 1567-1572. 1899 Sepahei, A.A. and Rashetnia, V., 2009. Tellurite Resistance and Reduction During Aerobic and 1900 Anaerobic Growth of Bacteria Isolated from Sarcheshme Copper Mine. Iranian Journal 1901 of Environmental Health, Science and Engineering, 6(4): 253-260. 1902 Shackleton, J.M., Spry, P.G. and Bateman, R., 2003. Telluride mineralogy of the golden mile 1903 deposit, Kalgoorlie, Western Australia. The Canadian Mineralogist, 41(6): 1503-1524. 1904 Shannon, R.D. and Prewitt, C.T., 1969. Effective ionic radii in oxides and fluorides. Acta 1905 Crystallographica Section B, 25(5): 925-946. 1906 Sharma, V.K., McDonald, T.J., Sohn, M., Anquandah, G.A., Pettine, M. and Zboril, R., 2015. 1907 Biogeochemistry of selenium. A review. Environmental chemistry letters, 13(1): 49-58. 1908 Shibasaki, T., Abe, K. and Takeuchi, H., 1992. Recovery of tellurium from decopperizing leach 1909 solution of copper refinery slimes by a fixed bed reactor. Hydrometallurgy, 29(1-3): 1910 399-412. 1911 Shuster, J. and Reith, F., 2018. Reflecting on Gold Geomicrobiology Research: Thoughts and 1912 Considerations for Future Endeavors. Minerals, 8(9): 401. 1913 Shuva, M., Rhamdhani, M., Brooks, G., Masood, S. and Reuter, M., 2016. Thermodynamics 1914 data of valuable elements relevant to e-waste processing through primary and 1915 secondary copper production: a review. Journal of cleaner production, 131: 795-809. 1916 Sillitoe, R.H. and Thompson, J.F.H., 1998. Intrusion–Related Vein Gold Deposits: Types, 1917 Tectono ‐ Magmatic Settings and Difficulties of Distinction from Orogenic Gold 1918 Deposits. Resource Geology, 48(4): 237-250. 1919 Simmons, S.F. and Brown, K.L., 2006. Gold in magmatic hydrothermal solutions and the rapid 1920 formation of a giant ore deposit. Science, 314(5797): 288-291. 1921 Simon, G. and Essene, E.J., 1996. Phase relations among selenides, sulfides, tellurides, and 1922 oxides; I, Thermodynamic properties and calculated equilibria. Economic Geology, 1923 91(7): 1183-1208. 1924 Singh, A.K. and Sharma, S., 2000. Recent developments in the ligand chemistry of tellurium. 1925 Coordination Chemistry Reviews, 209(1): 49-98. 1926 Smith, D.G. and Nickel, E.H., 2007. A system of codification for unnamed minerals: Report of 1927 the Subcommittee for Unnamed Minerals of the IMA Commission on New Minerals, 1928 Nomenclature and Classification. The Canadian Mineralogist, 45(4): 983-990. 1929 Smith, D.J., Naden, J., Jenkin, G.R.T. and Keith, M., 2017. Hydrothermal alteration and fluid 1930 pH in alkaline-hosted epithermal systems. Ore Geology Reviews, 89: 772-779. 1931 Soudi, M.R., Ghazvini, P.T.M., Khajeh, K. and Gharavi, S., 2009. Bioprocessing of seleno- 1932 oxyanions and tellurite in a novel Bacillus sp. strain STG-83: A solution to removal of 1933 toxic oxyanions in presence of nitrate. Journal of hazardous materials, 165(1-3): 71- 1934 77. 1935 Southam, G., Lengke, M.F., Fairbrother, L. and Reith, F., 2009. The biogeochemistry of gold. 1936 Elements, 5(5): 303-307. 1937 Stolz, J.F., 2017. Gaia and her microbiome. FEMS microbiology ecology, 93(2). 1938 Subbotin, V., Vymazalová, A., Laufek, F., Savchenko, Y., Stanley, C., Gabov, D. and Plášil, J., 1939 2019. Mitrofanovite, Pt3Te4, a new mineral from the East Chuarvy deposit, Fedorovo- 1940 Pana intrusion, Kola Peninsula, Russia. Mineralogical Magazine, 83(4): 523-530. 1941 Sung, Y.-H., Ciobanu, C., Pring, A., Brügger, J., Skinner, W., Cook, N. and Nugus, M., 2007. 1942 Tellurides from Sunrise Dam gold deposit, Yilgarn Craton, Western Australia: a new 1943 occurrence of nagyágite. Mineralogy and Petrology, 91(3-4): 249-270. 1944 Sung, Y.-H., Brugger, J., Ciobanu, C., Pring, A., Skinner, W. and Nugus, M., 2009. Invisible gold 1945 in arsenian pyrite and arsenopyrite from a multistage Archaean gold deposit: Sunrise 1946 Dam, Eastern Goldfields Province, Western Australia. Mineralium Deposita, 44(7): 765. 1947 Tagami, K., Uchida, S., Ishii, N. and Zheng, J., 2013. Estimation of Te-132 distribution in 1948 Fukushima Prefecture at the early stage of the Fukushima Daiichi nuclear power plant 1949 reactor failures. Environmental science & technology, 47(10): 5007-5012. 1950 Takahashi, R., Matsueda, H., Okrugin, V.M., Shikazono, N., Ono, S., Imai, A., Andreeva, E.D. 1951 and Watanabe, K., 2013. Ore‐forming Ages and Sulfur Isotope Study of Hydrothermal 1952 Deposits in K amchatka, R ussia. Resource Geology, 63(2): 210-223. 1953 Tan, L.C., Nancharaiah, Y.V., van Hullebusch, E.D. and Lens, P.N., 2016. Selenium: 1954 environmental significance, pollution, and biological treatment technologies. 1955 Biotechnology advances, 34: 886–907. 1956 Tanaka, M., Arakaki, A., Staniland, S.S. and Matsunaga, T., 2010. Simultaneously Discrete 1957 Biomineralization of Magnetite and Tellurium Nanocrystals in Magnetotactic Bacteria. 1958 Applied and Environmental Microbiology, 76(16): 5526-5532. 1959 Taylor, A., 1996. Biochemistry of tellurium. Biological Trace Element Research, 55(3): 231-239. 1960 Taylor, D.E., 1999. Bacterial tellurite resistance. Trends in microbiology, 7(3): 111-115. 1961 Tenailleau, C., Pring, A., Etschmann, B., Brugger, J., Grguric, B. and Putnis, A., 2006. 1962 Transformation of pentlandite to violarite under mild hydrothermal conditions. 1963 American Mineralogist, 91(4): 706-709. 1964 Theisen, J., Zylstra, G.J. and Yee, N., 2013. Genetic evidence for a molybdopterin-containing 1965 tellurate reductase. Applied and environmental microbiology, 79(10): 3171-3175. 1966 Thompson, T.B., Trippel, A.D. and Dwelley, P.C., 1985. Mineralized veins and breccias of the 1967 Cripple Creek district, Colorado. Economic Geology, 80(6): 1669-1688. 1968 Tomkins, A.G., Pattison, D.R. and Frost, B.R., 2006. On the initiation of metamorphic sulfide 1969 anatexis. Journal of Petrology, 48(3): 511-535. 1970 Tooth, B., Brugger, J., Ciobanu, C. and Liu, W., 2008. Modeling of gold scavenging by bismuth 1971 melts coexisting with hydrothermal fluids. Geology, 36(10): 815-818. 1972 Tooth, B., Ciobanu, C.L., Green, L., O’Neill, B. and Brugger, J., 2011. Bi-melt formation and gold 1973 scavenging from hydrothermal fluids: An experimental study. Geochimica et 1974 Cosmochimica Acta, 75(19): 5423-5443. 1975 Tran, P.A. and Webster, T.J., 2013. Antimicrobial selenium nanoparticle coatings on polymeric 1976 medical devices. Nanotechnology, 24(15): 155101. 1977 Turner, R.J., 2001. Tellurite toxicity and resistance in Gram-negative bacteria. Recent research 1978 developments in microbiology: 69-77. 1979 Turner, R.J., Borghese, R. and Zannoni, D., 2012. Microbial processing of tellurium as a tool in 1980 biotechnology. Biotechnology advances, 30(5): 954-963. 1981 Ullah, H., Liu, G., Yousaf, B., Ali, M.U., Irshad, S., Abbas, Q. and Ahmad, R., 2018. A 1982 comprehensive review on environmental transformation of selenium: recent 1983 advances and research perspectives. Environmental geochemistry and health: 1-33. 1984 U.S. Department of Energy, 2019. Cadmium Telluride. Office of Energy Efficiency and 1985 Renewable Energy, Washington, DC, https://www.energy.gov/eere/solar/cadmium- 1986 telluride. 1987 USDOI, 2018. Final List of Critical Minerals 2018. Federal Register Archives, Document number 1988 2018-10667, pp. 23295-23296. 1989 https://www.federalregister.gov/documents/2018/05/18/2018-10667/final-list-of- 1990 critical-minerals-2018. 1991 Vaigankar, D.C., Dubey, S.K., Mujawar, S.Y., D’Costa, A. and S.K, S., 2018. Tellurite 1992 biotransformation and detoxification by Shewanella baltica with simultaneous 1993 synthesis of tellurium nanorods exhibiting photo-catalytic and anti-biofilm activity. 1994 Ecotoxicology and Environmental Safety, 165: 516-526. 1995 Van der Zee, F.P. and Cervantes, F.J., 2009. Impact and application of electron shuttles on the 1996 redox (bio)transformation of contaminants: A review. Biotechnology Advances, 27(3): 1997 256-277. 1998 Vikentyev, I., 2006. Precious metal and telluride mineralogy of large volcanic-hosted massive 1999 sulfide deposits in the Urals. Mineralogy and Petrology, 87(3-4): 305-326. 2000 Vrionis, H.A., Wang, S., Haslam, B. and Turner, R.J., 2015. Selenite protection of tellurite 2001 toxicity toward Escherichia coli. Frontiers in molecular biosciences, 2: 69. 2002 Wadgaonkar, S.L., Mal, J., Nancharaiah, Y.V., Maheshwari, N.O., Esposito, G. and Lens, P.N., 2003 2018. Formation of Se(0), Te(0), and Se(0)–Te(0) nanostructures during simultaneous 2004 bioreduction of selenite and tellurite in a UASB reactor. Applied microbiology and 2005 biotechnology, 102(6): 2899-2911. 2006 Wallier, S., Rey, R., Kouzmanov, K., Pettke, T., Heinrich, C.A., Leary, S., O’Connor, G., Tamas, 2007 C.G., Vennemann, T. and Ullrich, T., 2006. Magmatic fluids in the breccia-hosted 2008 epithermal Au-Ag deposit of Rosia Montana, Romania. Economic Geology, 101(5): 2009 923-954. 2010 Wallschläger, D. and Feldmann, J., 2010. 10: Formation, Occurrence, Significance, and 2011 Analysis of Organoselenium and Organotellurium Compounds in the Environment, 2012 Organometallics in environment and toxicology, pp. 319-364. 2013 Wang, S., 2011. Tellurium, its resourcefulness and recovery. Jom, 63(8): 90. 2014 Wang, T., Yang, L., Zhang, B. and Liu, J., 2010. Extracellular biosynthesis and transformation 2015 of selenium nanoparticles and application in H2O2 biosensor. Colloids and Surfaces B: 2016 Biointerfaces, 80(1): 94-102. 2017 Wang, X., Liu, G., Zhou, J., Wang, J., Jin, R. and Lv, H., 2011. Quinone-mediated reduction of 2018 selenite and tellurite by Escherichia coli. Bioresource technology, 102(3): 3268-3271. 2019 Wang, Z. and Becker, H., 2013. Ratios of S, Se and Te in the silicate Earth require a volatile- 2020 rich late veneer. Nature, 499(7458): 328. 2021 Watanabe, T., Tsuchiya, N., Oura, Y., Ebihara, M., Inoue, C., Hirano, N., Yamada, R., Yamasaki, 2022 S.-i., Okamoto, A. and Nara, F.W., 2012. Distribution of artificial radionuclides (110mAg, 2023 129mTe, 134Cs, 137Cs) in surface soils from Miyagi Prefecture, northeast Japan, following 2024 the 2011 Fukushima Dai-ichi nuclear power plant accident. Geochemical journal, 46(4): 2025 279-285. 2026 Watterson, J.R., Gott, G.B., Neuerburg, G.J., Lakin, H.W. and Cathrall, J.B., 1977. Tellurium, a 2027 Guide to Mineral Deposits. In: C.R.M. Butt and I.G.P. Wilding (Editors), Developments 2028 in Economic Geology. Elsevier, pp. 31-48. 2029 Wedepohl, K.H., 1995. The composition of the continental crust. Geochimica et cosmochimica 2030 Acta, 59(7): 1217-1232. 2031 Wei, T.Y., Chang, H.Y., Lee, Y.F., Hunga, Y.L. and Huang, C.C., 2011. Selective Tellurium 2032 Nanowire‐based Sensors for Mercury (II) in Aqueous Solution. Journal of the Chinese 2033 Chemical Society, 58(6): 732-738. 2034 Weil, M., 2018. Crystal structures of the triple perovskites Ba2K2Te2O9 and Ba2KNaTe2O9, and 2035 redetermination of the double perovskite Ba2CaTeO6. Acta Crystallographica Section 2036 E, 74(7): 1006-1009. 2037 White, C., Wilkinson, S.C. and Gadd, G.M., 1995. The role of microorganisms in biosorption of 2038 toxic metals and radionuclides. International Biodeterioration & Biodegradation, 35(1- 2039 3): 17-40. 2040 William, W.Y., Chang, E., Drezek, R. and Colvin, V.L., 2006. Water-soluble quantum dots for 2041 biomedical applications. Biochemical and biophysical research communications, 2042 348(3): 781-786. 2043 Williams, P.A., 1990. Oxide zone geochemistry. Ellis Horwood Limited, pp. 286. 2044 Woodhouse, M., Goodrich, A., Margolis, R., James, T., Dhere, R., Gessert, T., Barnes, T., Eggert, 2045 R. and Albin, D., 2013. Perspectives on the pathways for cadmium telluride 2046 photovoltaic module manufacturers to address expected increases in the price for 2047 tellurium. Solar Energy Materials and Solar Cells, 115: 199-212. 2048 Wray, D.S., 1998. The impact of unconfined mine tailings and anthropogenic pollution on a 2049 semi-arid environment–an initial study of the Rodalquilar mining district, south east 2050 Spain. Environmental Geochemistry and Health, 20(1): 29-38. 2051 Wu, X., 2004. High-efficiency polycrystalline CdTe thin-film solar cells. Solar energy, 77(6): 2052 803-814. 2053 Xu, W., Zhao, J., Brugger, J., Chen, G. and Pring, A., 2013. Mechanism of mineral 2054 transformations in krennerite, Au3AgTe8, under hydrothermal conditions. American 2055 Mineralogist, 98(11-12): 2086-2095. 2056 Xu, Y., Li, J., Tan, Q., Peters, A.L. and Yang, C., 2018. Global status of recycling waste solar 2057 panels: A review. Waste management, 75: 450-458. 2058 Yeh, K.-W., Huang, T.-W., Huang, Y.-l., Chen, T.-K., Hsu, F.-C., Wu, P.M., Lee, Y.-C., Chu, Y.-Y., 2059 Chen, C.-L. and Luo, J.-Y., 2008. Tellurium substitution effect on superconductivity of 2060 the α-phase iron selenide. Europhysics Letters, 84(3): 37002. 2061 Yoschenko, V., Ohkubo, T. and Kashparov, V., 2018. Radioactive contaminated forests in 2062 Fukushima and Chernobyl. Journal of Forest Research, 23(1): 3-14. 2063 Yu, H., Young, J., Wu, H., Zhang, W., Rondinelli, J.M. and Halasyamani, P.S., 2016. Electronic, 2064 crystal chemistry, and nonlinear optical property relationships in the dugganite 2065 A3B3CD2O14 family. Journal of the American Chemical Society, 138(14): 4984-4989. 2066 Yu, M.-Z., Chen, X.-G., Garbe-Schönberg, D., Ye, Y. and Chen, C.-T.A., 2019. Volatile 2067 Chalcophile Elements in Native Sulfur from a Submarine Hydrothermal System at 2068 Kueishantao, Offshore NE Taiwan. Minerals, 9(4): 245. 2069 Yurkov, V., Jappe, J. and Vermeglio, A., 1996. Tellurite resistance and reduction by obligately 2070 aerobic photosynthetic bacteria. Applied and environmental microbiology, 62(11): 2071 4195-4198. 2072 Zare, B., Sepehrizadeh, Z., Faramarzi, M.A., Soltany‐ Rezaee ‐ Rad, M., Rezaie, S. and 2073 Shahverdi, A.R., 2014. Antifungal activity of biogenic tellurium nanoparticles against 2074 Candida albicans and its effects on squalene monooxygenase gene expression. 2075 Biotechnology and applied biochemistry, 61(4): 395-400. 2076 Zeng, C., Ramos-Ruiz, A., Field, J.A. and Sierra-Alvarez, R., 2015. Cadmium telluride (CdTe) and 2077 cadmium selenide (CdSe) leaching behavior and surface chemistry in response to pH 2078 and O2. Journal of environmental management, 154: 78-85. 2079 Zhang, X. and Spry, P.G., 1994. Calculated stability of aqueous tellurium species, calaverite, 2080 and hessite at elevated temperatures. Economic Geology, 89(5): 1152-1166. 2081 Zhao, J., Brugger, J., Grundler, P.V., Xia, F., Chen, G. and Pring, A., 2009. Mechanism and 2082 kinetics of a mineral transformation under hydrothermal conditions: Calaverite to 2083 metallic gold. American Mineralogist, 94(11-12): 1541-1555. 2084 Zhao, J., Xia, F., Pring, A., Brugger, J., Grundler, P.V. and Chen, G., 2010. A novel pre-treatment 2085 of calaverite by hydrothermal mineral replacement reactions. Minerals Engineering, 2086 23(5): 451-453. 2087 Zhao, J., Brugger, J., Xia, F., Ngothai, Y., Chen, G. and Pring, A., 2013. Dissolution- 2088 reprecipitation vs. solid-state diffusion: Mechanism of mineral transformations in 2089 sylvanite,(AuAg)2Te4, under hydrothermal conditions. American Mineralogist, 98(1): 2090 19-32. 2091 Zheng, Y., Gao, S. and Ying, J.Y., 2007. Synthesis and cell ‐ imaging applications of 2092 glutathione‐capped CdTe quantum dots. Advanced Materials, 19(3): 376-380. 2093 Zientek, M.L., Fries, T.L. and Vian, R.W., 1990. As, Bi, Hg, S, Sb, Sn and Te geochemistry of the 2094 J-M Reef, Stillwater Complex, Montana: constraints on the origin of PGE-enriched 2095 sulfides in layered intrusions. Journal of Geochemical Exploration, 37(1): 51-73. 2096 Zonaro, E., Lampis, S., Turner, R.J., Qazi, S.J.S. and Vallini, G., 2015. Biogenic selenium and 2097 tellurium nanoparticles synthesized by environmental microbial isolates efficaciously 2098 inhibit bacterial planktonic cultures and biofilms. Frontiers in microbiology, 6: 584. 2099 Zonaro, E., Piacenza, E., Presentato, A., Monti, F., Dell’Anna, R., Lampis, S. and Vallini, G., 2017. 2100 Ochrobactrum sp. MPV1 from a dump of roasted pyrites can be exploited as bacterial 2101 catalyst for the biogenesis of selenium and tellurium nanoparticles. Microbial cell 2102 factories, 16(1): 215.

TABLES

Table 1: Selected Te minerals (including wt% to nearest % of Te for tellurides). A full table of Te minerals is presented in Supplementary Table 1.

Mineral name Ideal chemical formula Crystal Ideal Wt% symmetry Te* PRIMARY (TELLURIDES) Altaite PbTe Isometric 38 %

Calaverite AuTe2 Monoclinic 56 %

Cervelleite Ag4TeS Monoclinic 22 % Coloradoite HgTe Isometric 39 % Empressite AgTe Orthorhombic 54 %

Frohbergite FeTe2 Orthorhombic 82 %

Goldfieldite Cu10Te4S13 Isometric 33 %

Hessite Ag2Te Monoclinic 37 %

Kawazulite Bi2Te2Se Trigonal 34 %

Kostovite CuAuTe4 Orthorhombic 66 %

Krennerite Au3AgTe8 Orthorhombic 59 %

Melonite NiTe2 Trigonal 81 %

Montbrayite (Au,Ag,Sb,Bi,Pb)23- Triclinic 45-50 % (Te,Sb,Bi,Pb)38

Muthmannite AuAgTe2 Monoclinic 46 %

Nagyágite [Pb3(Pb,Sb)3S6](Au,Te)3 Monoclinic ~30 % Petzite Ag3AuTe2 Isometric 33 %

Rickardite Cu7Te5 Orthorhombic 59 %

Rucklidgeite PbBi2Te4 Trigonal 45 %

Stützite Ag5-xTe3; Hexagonal 43 % 0.24 x 0.36

Sylvanite (Au,Ag)≤ 2≤Te4 Monoclinic 60-61 % Tellurobismuthite Bi2Te3 Trigonal 48 %

Tetradymite Bi2Te2S Trigonal 36 % (ELEMENTAL) Tellurium Te Trigonal SECONDARY (TELLURITES) 3+ 4+ Emmonsite Fe 2(Te O3)3·3H2O Triclinic 3+ 4+ Mackayite Fe (Te 2O5)(OH) Tetragonal 1+ 4+ Magnolite Hg 2Te O3 Orthorhombic 4+ Moctezumite Pb(UO2)(Te O3)2 Monoclinic 4+ Paratellurite α-Te O2 Tetragonal 2+ 4+ Spiroffite Mn 2Te 3O8 Monoclinic 4+ Teineite CuTe O3·2H2O Orthorhombic 4+ Tellurite β-Te O2 Orthorhombic 3+ 4+ Zemannite Mg0.5ZnFe (Te O3)3 Hexagonal

·(3+n)H2O; 0 n 1.5

(TELLURATES) ≤ ≤ 3+ 6+ Burckhardtite Pb2(Fe Te )[AlSi3O8]O6 Trigonal 6+ Dugganite Pb3Zn3(AsO4)2(Te O6) Trigonal 6+ Jensenite Cu3Te O6·2H2O Monoclinic 6+ Khinite PbCu3(Te O6)(OH)2 Orthorhombic 6+ Markcooperite Pb2UO2(Te O6) Monoclinic 6+ Mcalpineite Cu3(Te O6) Isometric 6+ Ottoite Pb2Te O5 Monoclinic 6+ Quetzalcoatlite Zn6Cu3(Te O6)2- Trigonal (OH)6·AgxPbyClx+2y 6+ Timroseite Pb2Cu5(Te O6)2(OH)2 Orthorhombic 4+ 6+ Xocolatlite Ca2Mn 2(Te O6)2·H2O Monoclinic (MIXED-VALENCE) 4+ 6+ Carlfriesite CaTe 2Te O8 Monoclinic Tlapallite (Ca,Pb)3CaCu6- Trigonal 4+ 6+ [Te 3Te O12]2- 4+ (Te O3)2(SO4)2·3H2O

Table 2: Quantification of amounts of Te associated with common sulphides. Some measurements are averages across a range of samples, others particular to a specific locality.

Ideal Te content Mineral name chemical Detail/locality average Reference formula (mg/kg) Covellite CuS Average Up to 430 (Dill, 2010)

Chalcopyrite CuFeS2 Average Up to 70 (Dill, 2010) (George et al., Average < 1 2018) Broken Spur vent, (Butler and 45 Mid-Atlantic Ridge Nesbitt, 1999) Baita Bihor; (George et al., 1.9 epithermal 2018) Kanmantoo; (George et al., metamorphosed 1.9 2018) sulphide ore

Galena PbS Average Up to 200 (Dill, 2010)

Pyrite FeS2 Average Up to 70 (Dill, 2010) Volcanogenic massive sulphide Up to 860, often (Belousov et al., average, Yilgarn less than 2 2016) Craton, Western Australia Orogenic average, Up to 710, often (Belousov et al., Yilgarn Craton, less than 100 2016) Western Australia Pyrite, arsenian pyrite FeS2, (Keith et al., and Fe(S,As)2 Carlin average 573 2018) arsenopyrite and FeAsS compilation Epithermal high (Keith et al., sulphidation 343 2018) average Epithermal low (Keith et al., sulphidation 600 2018) average Epithermal alkaline (Keith et al., 546 average 2018) (Keith et al., Orogenic average 306 2018) (Keith et al., Porphyry average 26.3 2018) 4.0-20823 (i.e. Pyrite, As- Dongping, China, (Cook et al., FeS2 microinclusions deficient alkaline epithermal 2009a) of tellurides) Huangtuliang, 3.0-18285 (i.e. (Cook et al., China, alkaline microinclusions 2009a) epithermal of tellurides) Hougou, China, (Cook et al., 2.6-19.6 alkaline epithermal 2009a)

Pyrrhotite Fe1-xS Average Up to 60 (Dill, 2010)

(Cook et al., Sphalerite ZnS Average < 0.05 2009b) Magura epithermal (Cook et al., Au deposit, 16-665 2009b) Romania

Table 3: Concentrations of dissolved Te in geothermal and hydrothermal fluids.

Te Temperature Locality concentration Comments Reference (˚C) (µg/L) Three samples Reykjanes geothermal with chlorinity (Hardardóttir system, Iceland, at 284-295 16.5 to 18.5 close to that of et al., 2009) 1350– 1500 m depth seawater (0.51- 0.53 M). Lihir geothermal Lihir water also system, Papua New (Simmons and ∼260 Up to 4 contained up to Guinea, at depth Brown, 2006) 13 µg/L Au. ∼550 m Wairakei geothermal Used as a field (Simmons and system, New Zealand, ∼ 255 Up to 0.4 blank sample Brown, 2006) at depth ∼950 m Based on Pacmanus seafloor hot extrapolations springs field, Papua from samples (Binns et al., ∼ 55 3 to 18 New Guinea, at depth heavily 2004) ∼130 m contaminated by seawater (88%) 233-255 Liquid-vapour Up to 14,000 (homogenisation T) inclusion Unique liquid- Au–Te epithermal 358 340,000 vapour inclusion (Wallier et al., system of Roşia 2006) Montană, Romania Two co-existing 5,500 and low-density ND 180,000 vapour inclusions Porphyry Cu–Mo–Au The final stage of this stage and transitional mineralizing (Pudack et al., quartz–sericite–pyrite 278 ± 23 Up to 670,000 system is a Te- 2009) stage of the Nevados de rich high Famatina deposit sulphidation (northwest Argentina) system High- temperature gas High temperatures condensate fumaroles at the contained ca. (Okrugin et Avacha Volcano, ∼ 600 Up to 16,000 100 times more al., 2017) Kamchatka Peninsula, Te than low- Far East Russia temperature condensates Te in scarcely hydrothermally High-sulphidation altered rocks in hydrothermal system (Fulignati and 250–520 5000-19,000 correspondence of the La Fossa volcano Sbrana, 1998) to the highest- (Vulcano, Italy) temperature fumarolic vents Table 4: Microbiological identities, locations, and produced Te nanoparticle morphology for selected Te oxyanion-reducing forms of bacteria

Product of reduction, Genus and species, with strain Taxonomic Location collected (if applicable) nanostructure size in nm Reference or enzyme (if applicable) designation if applicable Aeromonas caviae ST Gram-negative rod Previously isolated Te0 (Castro et al., 2008) Sources such as rotting garlic, kitchen Te0 nanospheres and Aspergillus welwitschiae Fungus (Abo Elsoud et al., 2018) sink slime nanoellipsoids (~60) Gram-positive rod, Sediment slurries from Mono lake, Te0 nanospheres and Bacillus beveridgei (Baesman et al., 2009) facultative anaerobe California, USA nanorods Bacillus filicolonicus, B. Gram-positive rods, Sarcheshme copper mine in Kerman Te0 nanospheres (Sepahei and Rashetnia, 2009) laterosporus facultative anaerobes Province, Iran Mud samples from salt marsh bordering Gram-positive rod, Intracellular Te0 nanorods Bacillus halodenitrificans the Indian River inlet, in Rehoboth Beach, (Ollivier et al., 2008) facultative anaerobe (<100) Delaware, USA Anzali Lagoon in Gilan province, Iran Gram-positive rod, Te0; volatilisation of Bacillus pumilis and the Neidasht spring in the north of (Soudi et al., 2009) facultative anaerobe unspecified gases Iran Extracellular Te0 nanorods Gram-positive rod, Sediment slurries from Mono lake, (Baesman et al., 2006; Bacillus selenitireducens (<200) clustered into larger facultative anaerobe California, USA Baesman et al., 2007) rosettes Bacillus species, Enzyme STG- Gram-positive rod, Neidasht spring in the north of Iran (also Te0 (Etezad et al., 2009) 83 facultative anaerobe see above) Gram negative Extracellular Se0–Te0 heterotrophic non- Se-rich soils from agricultural fields in (Bajaj and Winter, 2014) Duganella violacienigra composite nanoparticles halophilic and aerobic India (~100) proteobacterium Obligate aerobic Erythrobacter litoralis photosynthetic Previously isolated Intracellular Te0 (Yurkov et al., 1996) bacterium Obligate aerobic Intracellular Te0 or resistant Erythromicrobium ezovicum photosynthetic Previously isolated but no apparent reduction, (Yurkov et al., 1996) bacterium depending on carbon source Erythromicrobium Obligate aerobic hydrolyticum, E. ramosum, E. Previously isolated Intracellular Te0 (Yurkov et al., 1996) photosynthetic bacteria sibiricum, E. ursincola Magnetospirillum magneticum Facultative anaerobic Coprecipitated Te0 and Previously isolated (Tanaka et al., 2010) strain AMB-1 magnetotactic spiral magnetite nanocrystals Drainage water from a metal refining Extracellular Te0 (100) and Ochrobactrum anthropi TI-2 Gram-negative rod(s) plant in Amagasaki City, Hyogo DMTe, DMDTe and (Kagami et al., 2012) and TI-3 Prefecture, Japan DMTeS Gram-negative rod, Dump of roasted (arseno)pyrites from Ochrobactrum sp. MPV1 Aerobic Intracellular Te0 (Zonaro et al., 2017) near a factory in Tuscany, Italy α-proteobacterium Sediment from the Er-Jen River in Tainan Paenibacillus Sp. Strain TeW Gram-positive rod County, Taiwan, contaminated by run-off Te0 (Chien and Han, 2009) from electroplating factories and smelters Pseudoalteromonas sp. strain Gram-negative aerobic Previously isolated from volcanic vents Te0; DMTe (Bonificio and Clarke, 2014) EPR3 rods Gram-negative Pseudomonas Kesterson Reservoir in the San Joaquin facultative anaerobic Te0; DMTe and DMDTe (Basnayake et al., 2001) fluorescens K27 Valley of California, USA rod Pseudomonas mendocina MCM Gram-negative rod Previously isolated Te0 (Rajwade and Paknikar, 2003) B-180 Photosynthetic Gram- Intracellular Te0 nanorods Rhodobacter capsulatus negative anaerobic α- Previously isolated (Borghese et al., 2016) (200-700) proteobacterium Aerobic Gram-positive Intracellular Te0 non- Rhodococcus aethivorans BCP1 Previously isolated (Presentato et al., 2016) sphere aggregated nanorods (<700) Mud samples from salt marsh bordering Obligately aerobic, Rhodotorula mucilaginosa the Indian River inlet, in Rehoboth Beach, Te0 (Ollivier et al., 2008) Gram-positive rods Delaware, USA Intracellular Te0 or resistant Obligately aerobic Roseococcus thiosulfatophilus Previously isolated but no apparent reduction, (Yurkov et al., 1996) photosynthetic sphere depending on carbon source Gram-positive Salinicoccus iranensis Previously isolated Te0 (Alavi et al., 2014) halophilic sphere Salty environments including saline or Gram-positive Salinicoccus sp. QW6 hypersaline soils, hypersaline brackish Intracellular Te0 (Amoozegar et al., 2008) halophilic sphere water and textile factory effluents of Iran Facultative Gram- Water from the Zuari Estuary, Goa state, Te0 nanorods (8-75 Shewanella baltica (Vaigankar et al., 2018) negative anaerobic rod India diameter) Kim: Intracellular Te0 Facultative Gram- (Kim et al., 2012a; Klonowska Shewanella oneidensis MR-1 Previously isolated nanorods (100-200); negative anaerobic rod et al., 2005) Klonowska: also intracellular (size unspecified) Pages: Te0 intracellularly; Pages: Isolated from contaminated Kagami: Te0 intracellularly Pseudomonas cultures; Kagami: Drainage and extracellularly (200- (Kagami et al., 2012; Pages et Stenotrophomonas maltophilia Gram-negative rod water from a metal refining plant in 300) and DMTe and al., 2011; Zonaro et al., 2015) Amagasaki City, Hyogo Prefecture, DMDTe; Zonaro: Te0 (75- Japan; Zonaro: Environmental isolates 80) Extracellular Te0 Sediment slurries from Mono lake, nanospheres (<50) Sulphurospirillum barnesii Anaerobic spiral (Baesman et al., 2006) California, USA coalescing into larger composites

Abbreviations: Te0 – solid elemental tellurium, DMTe – gaseous dimethyl telluride, DMDTe – gaseous dimethyl ditelluride and DMTeS – gaseous dimethyl tellurenyl sulphide. Ordered by scientific name. FIGURES AND CAPTIONS

Figure 1: Visual and chemical diversity of Te minerals. Three primary minerals: (a) Calaverite (AuTe2) from Cripple Creek, Colorado, USA, field of view (FOV) 1.3 mm, (b) Krennerite (Au3AgTe8) also from Cripple Creek, FOV 3 mm and (c) Sylvanite [(Au,Ag)2Te] from Emperor Mine, Viti Levu, Fiji, FOV 5 mm. (d) One example of elemental Te with the 4+ wsecondary mineral, teineite (CuTe O3·2H2O) from Teine Mine, Japan, FOV 3 mm. Finally, 3+ 4+ two secondary minerals: (e) Zemannite [Mg0.5ZnFe (Te O3)3·(3+n)H2O)], from Moctezuma 2+ 6+ mines, Mexico, FOV 2 mm and (f) Jensenite (Cu 3Te O6·2H2O) from Centennial Eureka Mine, Utah, USA, FOV 1 mm. Images credit Brent Thorne.

Figure 2: a) World consumption of Te, showing the dramatic growth in Te usage over the past decade in thermoelectric devices and photoreceptors, with cadmium telluride (CdTe) solar panels one of the main drivers. a) Reproduced from Figure 1 of (Nuss, 2019). b) One of the many new CdTe solar panel arrays: a solar-powered pump in the village of Angarf, Ouarzazate Province, Morocco. Image credit Georges Favreau.

Figure 3: The wide variety of bonding Te participates in contributes to its rich surface chemistry. Te participates in intermetallic bonding between elements like Ag, Au, and other Te atoms in primary minerals. Te also forms a variety of arrangements with oxygen, with different bonding modes for Te4+ and Te6+. The bonding arrangements between Te and O are further explored in Figure 4.

Figure 4: Various Te–O bonding networks as illustrated by Te4+ minerals (see Supp. table 1 for formulae). The bonding networks vary from simple, finite units to complex, three-dimensional structures. All structures except cyclo are known in minerals, with the simplest neso compounds forming the largest number of structures across both Te4+ and Te6+ minerals. Although other ligands may bind to Te4+ and Te6+ in synthetic contexts, in minerals, all strong bonds are to oxygen atoms.

Figure 5: Tellurium environmental cycling schematic, bringing together the various sinks of Te (highlighted in green) and the processes and transformations which occur between different Te reservoirs (highlighted in pink). Particularly high concentrations of Te are found in volcanogenic sulphur, some ore deposits and in Cu concentrates and anode slimes during some Cu processing. The complex biological interactions shown in the top part of the diagram are further explored in Section 6. a(Anders and Grevesse, 1989); b (McDonough and Sun, 1995); c (Hattori et al., 2002); d (Hu and Gao, 2008); e (Dill, 2010); f (Maslennikov et al., 2013); g (Hein et al., 2003); h (Goldfarb et al., 2017); i (Makuei and Senanayake, 2018); j (Kavlak and Graedel, 2013); k (Nuss, 2019); l (Filella et al., 2019); m (Belzile and Chen, 2015); and n (Ba et al., 2010).

Figure 6: World map showing locations of selected tellurium-enriched mineral occurrences, by deposit type. The deposit types shown here are classified as follows: volcanogenic massive sulfide (VMS), iron oxide-copper-gold (IOCG), orogenic gold, porphyry, epithermal, skarn, Carlin- type gold, magmatic copper–nickel–platinum-group metal (Cu-Ni-PGM), and other deposit types (43, 46 and 50, Te-rich waste from massive sulphide ores; 79 and 81, Intrusion-related Au deposit). Adapted from mindat.org, Goldfarb et al. (2017) and Keith et al. (2018), using the crust- type world map template of the USGS (https://earthquake.usgs.gov/data/crust/type.html).

Figure 7: Solubility of various Te species at ~1 (solid red lines) and 100 ppb levels (dashed red lines) as a function of pH and oxygen fugacity at (a) 25 and (b) 300 °C and water-saturated pressures, using thermodynamic properties collected by McPhail (1995) and Grundler et al. (2013). The Fe diagram in a Fe-S-Cl-O-H system is drawn as blue dashed lines for reference (conditions listed in the legend inset). The S diagram is shown as purple dashed lines. Abbreviations in top two diagrams: py - pyrite; hm - hematite; mt - magnetite; po – pyrrhotite. Horizontal dotted lines at the top and bottom of the two diagrams indicate the stability field of

H2O.

Figure 8: Formation of secondary Te minerals at the young (6.9–7.1 My) Aginskoe deposit, in the active volcanic arc in the Kamchatka Peninsula, Russia. (A) Rich assemblage of secondary Te minerals are found in a restricted part of the oxidation zone. (B) Weathering of a chalcopyrite grain containing petzite inclusion. The rim (labelled o-cpy) consists of poorly crystallised, inhomogeneous and Te-bearing Fe-Cu-oxy-hydroxides, containing inclusions of fine-grained native gold. (C,D) Microporous gold resulting from the dealloying of primary Te minerals, most likely calaverite; some of the pores are filled with a Te-rich phase, probably tellurite. (B-D) images are modified after Okrugin et al. (2014); (A) microphotograph provided by Prof. V. Okrugin.

Figure 9: Moctezuma, Sonora, Mexico, is famous for the abundance and diversity of tellurium minerals. (A) On the first few meters below the surface, intense weathering results in the formation of abundant Fe(Mn)-oxy-hydroxides; these are shown by portable-XRF to contain high amounts of Te (>>100 ppm); however, no visible secondary mineral was observed. Below this level, native tellurium was observed undergoing weathering to tellurite (TeO2) and probably other secondary minerals in smaller amounts. (B) Native tellurium (here in a calcite matrix) is the most prominent primary (hydrothermal) Te mineral. (C) Tellurite is one of the most prominent secondary minerals, here in millimetre-size blades. Image credit Stefan Ansermet.

Figure 10: Log scale 132Te concentration contour maps in the eastern part of Fukushima Prefecture showing the distribution of the anthropogenic and radioactive isotope 132Te around the Fukushima Daiichi Nuclear Power Plant (FDNPP) (decay-corrected to March 11, 2011) showing (a) Measured 132Te; (b) estimated from 129mTe, and (c) all data including MEXT. Figure adapted from Tagami et al. (2013)

Figure 11: A schematic of a ‘super-microorganism’ capable of mediating the key processes microbes participate in with Te that control its immobilisation and mobilisation; these include bioaccumulation, bioprecipitation, bioreduction, biovolatilisation and biooxidation. Biosorption controls the initial step of interaction between any microorganism and Te, while bioreduction is the most common detoxification step.

Figure 12: Mono Lake, California. Three Te-oxyanion reducing bacteria (Bacillus beveridgei, B. selenitireducens and Sulphurospirillum barnesii, see Table 2) have been found from the saline and alkaline waters of this lake (Baesman et al., 2006; Baesman et al., 2009; Baesman et al., 2007). Note that the salinity is so high that evaporites precipitate onto the rocks sitting above the water line. Image credit Mark L Dodge.

Figure 13: Reproduced (with slight formatting modifications) pictures of Te nanostructures produced by bioprecipitation. (a) SEM micrographs of Te nanospheres and a cluster of Te nanorods produced by Bacillus beveridgei. From Figure 2 of Baesman et al. (2009). (b) TEM micrograph of Te nanorods produced aerobically by Rhodococcus aetherivorans, visible protruding outwards from a single cell. From Figure 3b of Presentato et al. (2016). (c) SEM micrographs of SeTe nanospheres produced by Duganella violacienigra (C4 label on right hand side indicates culture number in original paper). From Figure 4a of Bajaj and Winter (2014).

Figure 14: Postulated model for Te and Au cycling in the regolith, modified after the gold dispersion model from Figure 2 of (Rea et al., 2016). Note the major difference between the two elements is that Te can be made airborne by microbes in the form of dimethyl telluride or other alkylated forms of Te, whereas Au remains in the soil or groundwater.