116 Journal ofM. Mineralogical Ohnishi, N. Shimobayashi, and Petrological S. Kishi, Sciences, M. Tanabe Volume and 108, S. pageKobayashi 116─ 120, 2013 LETTER Talmessite from the Uriya deposit at the Kiura mining area, Oita Prefecture, Japan * ** *** Masayuki OHNISHI , Norimasa SHIMOBAYASHI , Shigetomo KISHI , † § Mitsuo TANABE and Shoichi KOBAYASHI * 12-43 Takehana Ougi-cho, Yamashina-ku, Kyoto 607-8082, Japan **Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan *** Kamisaibara Junior High School, 1320 Kamisaibara, Kagamino-cho, Tomada-gun, Okayama 708-0601, Japan † 2058-3 Niimi, Niimi, Okayama 718-0011, Japan § Department of Applied Science, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan Talmessite was found in veinlets (approximately 1 mm wide) cutting into massive limonite in the oxidized zone of the Uriya deposit, Kiura mining area, Oita Prefecture, Japan. It occurs as aggregates of granular crystals up to 10 μm in diameter and as botryoidal aggregates up to 0.5 mm in diameter, in association with arseniosiderite, and aragonite. The talmessite is white to colorless, transparent, and has a vitreous luster. The unit-cell parame- ters refined from powder X-ray diffraction patterns are a = 5.905(3), b = 6.989(3), c = 5.567(4) Å, α = 96.99(3), β = 108.97(4), γ = 108.15(4)°, and Z = 1. Electron microprobe analyses gave the empirical formula Ca2.15(Mg0.84 Mn0.05Zn0.02Fe0.01Co0.01Ni0.01)∑0.94(AsO4)1.91·2H2O on the basis of total cations = 5 apfu (water content calculated as 2 H2O pfu). It is suggested that the talmessite formed as a secondary mineral derived from löllingite, calcite, and diopside. Keywords: Talmessite, Secondary mineral, Arsenate, Uriya deposit, Kiura INTRODUCTION ported by Catti et al. (1977). Joswig et al. (2004) also not- ed the structure of ‘talmessite,’ but the material was in Talmessite, a rare calcium-magnesium arsenate mineral, fact beta-roselite, which contains more Co than Mg. was first described from the oxidized zone of the Talmessi During fieldwork at the Uriya deposit of the Kiura mine, Iran by Bariand and Herpin (1960). They are also mining area, Japan, two of the present authors (S.K. and noted cobaltoan talmessite from Bou Azzer, Morocco. M.T.) recognized a white to colorless mineral. Powder X- The mineral was subsequently reported from Tsumeb, Na- ray diffraction (XRD) and electron microprobe analyses mibia (Sturman and Dunn, 1980), Kővágószőlős, Hunga- confirmed the mineral to be talmessite. This is the first ry (Szakáll et al., 1994), the Khovu-Aksy Ni-Co deposit, discovery of talmessite in Japan. The present paper pro- Russia (Pekov et al., 2001), and other localities. With an vides a mineralogical description of the talmessite and ideal formula of Ca2Mg(AsO4)2·2H2O, talmessite is a discusses its genesis. member of the fairfieldite group. The chemical formula of this group is generally represented by Ca2M(XO4)2·2H2O OCCURRENCE 2+ 2+ (where M = Co, Fe , Mg, Mn , Ni, or Zn and X = As or_ P), and the crystal system is triclinic with space group P1. The Uriya deposit is located in the eastern part of the Kiu- Talmessite is the Mg-dominant analogue of beta-roselite ra mining area at Kiura-Kozan, Ume, Saiki City, Oita (M = Co), gaitite (Zn), parabrandtite (Mn2+), and nickel- Prefecture, Kyushu, Japan (32°48′N, 131°33′E). The de- talmessite (Ni). The crystal structure of talmessite was re- posit had been worked mainly for arsenic. The ore body is a skarn-type deposit of limestone and slate belonging to doi:10.2465/jmps.121022g the Chichibu terrane and is intruded by Late Miocene M. Ohnishi, [email protected] Corresponding author Okueyama granite. The ore and gangue minerals are pre- Talmessite from the Uriya deposit at Kiura, Japan 117 Figure 1. A photograph of talmessite from the Uriya deposit. Color version of Figure 1 is available online from http://japanlinkcen ter.org/DN/JST.JSTAGE/jmps/121022g. dominantly löllingite, calcite, quartz, wollastonite, and fluorite, with lesser amounts of arsenopyrite, scheelite, cassiterite, sphalerite, gold, bismuth, diopside, vesuvian- ite, grossular, and others (Miyahisa, 1962). The oxidized zone of the deposit consists chiefly of limonite formed by oxidization of löllingite, and following secondary miner- als have been recognized: arseniosiderite, bendadaite, conichalcite, ferrarisite, ‘ferrisymplesite,’ guérinite, karibibite, parasymplesite, pharmacolite, pharmacosider- ite, phaunouxite, picropharmacolite, scorodite, symple- site, and others (e.g., Ito et al., 1932; Ito et al., 1954; Fuji- wara et al., 2009; Matsubara et al., 2009; Uehara et al., Figure 2. A photomicrograph (crossed nicol) (a), a back-scattered 2010). electron image (BEI) (b), and element-distribution maps (c)-(g) Talmessite was found in veinlets cutting into mas- of talmessite and its associated minerals from the Uriya deposit. Abbreviations: Tlm, talmessite; Arg, aragonite; Ass, arseniosid- sive limonite near crystalline limestone in the oxidized erite; Lmn, limonite. zone. The veinlets are approximately 1 mm wide at the adit wall, and consist mainly of talmessite, arseniosiderite, and aragonite. The talmessite occurs as aggregates of granular crystals up to 10 μm in diameter and as botryoi- dal aggregates up to 0.5 mm in diameter in cavities in the veinlets (Figs. 1 and 2). The massive limonite also in- cludes other arsenate minerals, such as scorodite, pharma- cosiderite, and picropharmacolite. PHYSICAL PROPERTIES Talmessite from the Uriya deposit is white to colorless, transparent, and has a vitreous luster. Cleavage was not observed. The density, calculated from refined unit-cell parameters and the empirical formula, is 3.44 g/cm3. The Fourier transform-infrared absorption (FT-IR) Figure 3. FT-IR spectrum of talmessite from the Uriya deposit. spectrum was measured using a JASCO MET-680 FT-IR spectrometer with the KBr pellet method for the region of 4000 cm−1 to 400 cm−1 (Fig. 3). The broad absorption 118 M. Ohnishi, N. Shimobayashi, S. Kishi, M. Tanabe and S. Kobayashi −1 −1 bands at 3410 cm and 2950 cm are attributed to O-H present talmessite are absent in the pattern reported by stretching vibrations. The absorption bands at 970 cm−1, Pekov et al. (2001), the cell parameters agree well. −1 −1 860 cm , and 810 cm are attributed to AsO4 stretching −1 vibrations, and the band at 435 cm is attributed to AsO4 CHEMICAL COMPOSITION bending vibrations. Chemical analyses were carried out using a JEOL JXA- X-RAY DIFFRACTION 8105 electron microprobe analyzer with wavelength-dis- persive spectrometry (WDS) at Kyoto University (15 kV, Powder XRD data were obtained using a Rigaku Smart- 1 nA, and 5 μm beam diameter). Element-distribution Lab-SS diffractometer at Kyoto University with Ni-fil- mapping was also carried out using the WDS (Figs. 2c- tered CuKα radiation (40 kV and 40 mA). Based on 2g). Standard materials were wollastonite (Ca), periclase talmessite reported by Catti et al. (1977), the refractions (Mg), rhodonite (Mn), hematite (Fe), skutterudite (Co), of the mineral were indexed on the triclinic cell. The XRD pentlandite (Ni), sphalerite (Zn), synthetic GaAs (As), ap- data and unit-cell parameters refined by least squares are atite-(CaF) (P), and quartz (Si). All data were corrected listed in Table 1 and are compared with those of talmess- with a ZAF method. The water content was calculated as ite having near end-member composition reported by Pe- 2 H2O pfu. The average of five analyses is listed in Table kov et al. (2001). Although some diffraction lines for the 2. The empirical formula of the talmessite is Ca2.15(Mg0.84 Table 1. Representative powder XRD data for talmessite 1. Uriya deposit, Japan (present work). 2. Khovu-Aksy Ni-Co deposit, Russia (Pekov et al., 2001). Talmessite from the Uriya deposit at Kiura, Japan 119 3− Table 2. Chemical analyses of talmessite from the Uriya deposit AsO4 -bearing solution and limonite; (4) talmessite crys- 2+ 2+ 3− tallized from Ca , Mg , and AsO4 -bearing solution; and (5) associated aragonite crystallized from the residual liq- 2+ 2− uid containing Ca and CO3 after crystallization of talmessite, which does include carbonate. Talmessite from the Talmessi mine (Bariand and Herpin, 1960) and the Khovu-Aksy Ni-Co deposit (Pekov et al., 2001) is near the end-member composition. Talmessite-beta-roselite solid solution [Mg/(Mg + Co) = 0.65 (Bariand and Herpin, 1960), 0.45 (Joswig et al., 2004)] and talmessite-gaitite solid solution [Zn/(Mg + Zn) = 0.86 to 0.36 (Sturman and Dunn, 1980)] have also been reported. The present talmessite contains small amounts (less than 0.05 apfu) of Mn, Fe, Co, Ni, Zn, P, * Analyzed points. and Si. Generally, arsenate fairfieldite group minerals ** - Calculated as 2 H2O pfu. have low FeO contents : e.g., 0.32 wt% for beta roselite (Frondel, 1955); 0.2 wt% for gaitite (Sturman and Dunn, Mn0.05Zn0.02Fe0.01Co0.01Ni0.01)∑0.94(AsO4)1.91·2H2O on the ba- 1980) and parabrandtite (Dunn et al., 1987); and not given sis of total cations = 5 apfu. Although the Ca content is in for talmessite (Bariand and Herpin, 1960; Pierrot, 1964; excess, the formula is consistent with the ideal formula of Pekov et al., 2001) and nickeltalmessite (Chukanov et al., talmessite. 2009). These minerals also were not allocated Fe2O3 in the literature. From the data, it is likely that the minerals 3+ 3− DISCUSSION excluded Fe . Under the conditions in which AsO4 forms from primary arsenide minerals, Fe may easily be oxi- 3+ The talmessite-bearing massive limonite at the Uriya de- dized to Fe . Even if the environment is Fe-rich, the ar- posit is generally accompanied by various arsenate miner- senate fairfieldite group minerals remain free of or have als, such as scorodite, pharmacosiderite, arseniosiderite, only low amounts of Fe.