MINING GEOLOGY,39(6),355•`372,1989

Occurrence and Chemistry of Indium-containing Minerals from the Toyoha Mine, Hokkaido, Japan

Eijun OHTA*

Abstract: Toyoha lead-zinc-silver vein-type deposit in Hokkaido, Japan produces an important amount of indium

as well as tin and copper. Bismuth, tungsten, antimony, arsenic, and cobalt are minor but common metals. Indium

minerals recognized are; unnamed Zn-In mineral (hereafter abbreviated as ZI) whose composition is at the midst of

sphalerite and roquesite, unnamed Ag-In mineral (AI) of AglnS2 composition, roquesite (RQ) and sakuraiite.

Observed maximum weight percentages of indium in chalcopyrite, kesterite (KS) and stannite are 1.0, 1.86 and 20.0,

respectively. Indium concentration in sphalerite ranges from O.On to a few weight percent in most case, but exceeds

ten weight percent at some points. Detailed EPMA analyses have revealed that such high concentration is attributed

to a continuous solid solution between sphalerite (SP) and ZI. Continuous solid solutions between RQ90ZI10 and RQ37ZI69, and between KS100ZI0 and KS30ZI70 are also detected. These solid solutions are attributed to coupled

substitutions of 2(Zn, Fe) for CuIn, and of (Zn, Fe)In for CuSn. Other substitutions found between chalcopyrite

and stannite and between stannite/kesterite and roquesite are of (Fe+2, Zn)Sn for 2Fe+3 and of (Fe+2, Zn)Sn for

2In respectively. Economically most important indium carriers in Toyoha are ZI and indium-bearing sphalerite.

Next to sphalerite are kesterite, stannite and the anisotropic chalcopyrite. The occurrence of these minerals indicates

that these minerals have been formed by pulsatile mineralization whose peak temperatures were 50 to 100•Ž higher

than the hitherto estimated maximum formation temperature, about 300•Ž, of the deposit.

Introduction (KANBARAet al., 1989). In addition, the later- stage veins in the southeast produce antimony, The Toyoha mine is located 40 km south- arsenic, tin, indium, bismuth, tungsten, cobalt west of Sapporo, Hokkaido, Japan. The lead- and molybdenum (YAJIMA,1977; OHTA, 1980; zinc-silver veins are Pliocene to Pleistocene in OHTAet al., 1987; NARUIet al., 1988). The over- age as indicated by potassium-argon dating all zonal distribution of these metals is con- (SAWAIand ITAYA,1989), and are probably re- cordant to that of silver minerals (YAJIMAand lated to a series of latent intrusions (NEDO, OHTA, 1979; YOSHIEet al., 1986), of gangue 1988) which appear to be the heat source of minerals (OHTA and MARUMO1985), and of current extensive geothermal activity around fluid inclusion data (YAJIMAand OHTA, 1979). the mining area. Two formation stages of the This indicates that indium from Toyoha is veins have been discriminated (AKOMEand related to the later-stage mineralization which HARAGUCHI,1963, 1967; MIYAJIMAet al., 1971; centered on the southeastern border of the HASHIMOTOet al., 1977). Veins of both stages vein swarm. The, average indium content in the produce subordinate amount of manganese in crude ore from Toyoha is as high as 250 ppm the northwest of the vein swarm, while a high- (YOSHIEet al., 1986), which is comparable to grade copper (more than one weight percent that in zinc concentrates (not in crude ore) of Cu) zone is recognized in the Shinano and some representative indium producers in cen- Izumo veins on the southeast of the swarm tral Peru (SOLER,1987). It should be empha- sized that the indium grade is far higher in the Received on June 17, 1989, accepted on November 10, later-stage veins (YOSHIEet al., 1986; NARUIet 1989 * Geological Survey of Japan al., 1988). This paper presents the occurrence , Hokkaido Branch, Kita-8 Nishi-2, Kita-ku, Sapporo, 060 Japan. and chemistry of indium-containing minerals Keywords: Toyoha vein-type deposit, Indium, Tin, from Toyoha to clarify the distribution and Roquesite, Solid solution, Formation temperature. mode of occurrence of indium in ore minerals.

355 356 E. GHTA MINING GEOLOGY:

Chemical features of newly identified solid and tin minerals are discussed. solutions of the indium-containing minerals, Mineralization Stages of the and the formation temperature of the indium Toyoha Deposit

Table 1 Tin and indium minerals recognized in the Indium minerals commonly accompany tin Toyoha deposit. minerals, and those from Toyoha are not ex- CP-ST ss: chalconvrite-stannite solid solution ceptions. By this time seventeen tin and/or in- dium minerals have been recognized in the Toyoha deposit (Table 1). As already noted, these minerals are concentrated in the later- stage veins distributed in the southeast of the deposit, namely, Shinano, Izumo, Sorachi, and southern half of Soya (Fig. 1). The later- stage mineralization is subdivided into three (OHTA, 1980) or five (KANBARAet al., 1989) substages. Although the detail of subdivision is not confirmed yet, the sequence of the later- stage mineralization is summarized as follows: A Characteristic minerals formed in this substage are pyrrhotite and iron-rich sphale- rite. This corresponds to the substage III-a in KANBARAet al. (1989), and to the substage I in OHTA (1980). * New mineral (YAM et al., in prep.) B This substage is characterized by tin and

Fig. 1 Vein system of the Toyoha deposit (modified after NARUIet al., 1988). Harima, Tajima and Chikugo No. 3 are the earlier veins, while Shinano, Izumo, Sorachi and Soya are the later. 39(6), 1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine 357 indium minerals associated with chalcopyrite, microscope, the Zn-In mineral exhibits a sphalerite, galena, wolframite, and arsenopy- slight brown tint as compared with sphalerite, rite. KANBARA'S III-b and IV. OHTA's substage and shows imperceptible to weak anisotro- II. pism, but no bireflectance nor internal reflec- C Substage of silver sulfosalts such as tion. Its polishing hardness is similar to that of pyrargyrite, diaphorite and freibergite asso- sphalerite. Indium sphalerite is commonly ciated with galena and sphalerite. KANBARA'S observed as thin growth bands within normal V. OHTA'S substage III. sphalerite, and exhibits various colors between D Recognized only in northern halt of the those of normal sphalerite and the Zn-In Soya vein. Sphalerite and galena in this mineral. Though boundaries of the Zn-In substage are not associated with silver, tin nor mineral against the other two are generally indium minerals. KANBARA'S VI. sharp, indium sphalerite frequently shows E This is recognized mainly in the northwest gradational boundaries to normal sphalerite. of the deposit, and is characterized by man- Fig. 3-A shows a back-scattered electron im- ganese minerals. KANBARA'S VII. age of rhythmically zoned indium sphalerite. Chalcopyrite-stannite solid solutions Occurrences and Microscopic Observations (substage B): of Indium-Containing Minerals Two optically different types of chalco- Ag-In mineral (substage C): pyrite, isotropic and anisotropic, occur in the The unnamed Ag-In mineral is rarely and Toyoha deposit (KASE, 1987). The isotropic locally recognized at middle to upper levels of one has an almost ideal chemical composition the Sorachi vein where intense silver mineral- CuFeS2, and occurs dominantly throughout ization has followed that of tin and indium. It the Toyoha deposit, while the anisotropic one occurs in close association with hocartite, gale- is recognized only in deep levels of the south- na, pyrargyrite and pyrite as metasome which eastern veins. As shown in Figs. 2-A, 2-B, 3- has partly replaced the Zn-In mineral or indi- B and 3-D, the anisotropic chalcopyrite is um-bearing sphalerite (hereafter expressed as always associated with tin and/or indium indium sphalerite). This suggests that the for- minerals, and contains tin, indium and zinc in mation of the Ag-In mineral is due to a reac- itself. The anisotropy is presumably due to tion between indium minerals of the substage distortion of the cell caused by these minor B and the silver-rich ore solution of the sub- components. Microprobe work has identified stage C (OHTA, 1980). As compared with ho- additional two phases; stannite with slightly cartite, the Ag-In mineral has similar pol- more chalcopyrite molecule than normal one, ishing hardness, and shows a slightly more red and an unnamed phase (CP-ST ss) whose data tint. Its anisotropism is strong, but bireflec- are plotted between chalcopyrite and stannite tance is not observed. (Fig. 5). As well as the anisotropic chalcopy- Zn-In mineral and indium sphalerite rite, this phase is distributed mainly in deep (substage B): levels of the southeastern veins, and always The unnamed Zn-In mineral has a chemical exhibits complex intergrowth with stannite and composition at the midst of sphalerite and ro- the anisotropic chalcopyrite (Figs. 2-D, 3-F, quesite. It is common in the later-stage veins, 4-F). Its color is similar to that of stannite, and usually occurs within sphalerite (OHTA, but anisotropism is much stronger. 1980). It generally shows concentric parallel in- Stannite, kesterite (substage B) and hocartite tergrowth with normal and indium sphalerite. (substage C): Stannite, kesterite, and chalcopyrite often ac- Optical characters of stannite and kesterite company them. A unit band., of the Zn-In are similar to those described in UYTENBOGA- mineral is as wide as 50 microns at lower levels ARDTand BURKE(1971). Comparison of the of the veins, but is quite thin, generally ten microscopic observations and chemical ana- microns or less, at upper levels. Under ore lyses have proved that Zn/Fe+Zn ratios of 358 E. OHTA MINING Gioiixn:

Fig. 2 Microphotographs of indium-containing minerals from Toyoha. Bars at the upper right corners of the pic- tures are 50 micrometers long. 2-A: Zoning of the anisotropic chalcopyrite (CP) and indium-rich stannite (ST) in the sample B409. TE: tetrahedrite. 2-B: Ditto. Crossed Nicols. 2-C: Dendritic Cu-Zn-Fe mineral (CZF) included within the anisotropic chalcopyrite (CP) from -550 meter level of the Soya vein. RQ: aggregate of roquesite, the Zn-In mineral, kesterite, and solid solutions between them. 2-D: Growth zoning of the CP-ST solid solution (CP-ST, mostly at the core) and stannite (ST). Boundaries bet- ween them are not easily recognizable in this picture. Crossed Nicols. CP: chalcopyrite, SP: sphalerite. these minerals are negatively correlated to which includes cassiterite and/or stannite strength of both anisotropism and bireflec- grains. This indicates that hocartite is a prod- tance, and to degree of brown tints. Stannite uct of a reaction between the tin minerals of and kesterite are as common as the Zn-In the substage B and the silver-rich hydro- mineral in the later-stage veins. Stannite thermal solution of the substage C. dominates over kesterite at upper levels, while Roquesite and sakuraiite (substage B): the amount of kesterite and maximum Zn/ Roquesite and sakuraiite are recognized in a Fe + Zn ratios in kesterite increase downward copper-rich ore from -550 meter level of a and southeastward. At deep levels, stannite southern part of the Soya vein. They occur as tends to coexist with the anisotropic chalcopy- bands or grains intergrown with kesterite and rite and the CP-ST ss, while kesterite occurs the Zn-In mineral. It is difficult to distinguish together with indium sphalerite and the Zn-In one from the other under optical microscope mineral as discrete grains or concentric paral- because these four minerals are generally mix- lel bands within sphalerite. As well as other ed within a composite grain or band (Fig. 3-E). silver minerals, hocartite is often observed When compared with other three minerals, ro- within hydrothermally etched pits in sphalerite quesite shows a distinct blue tint and clear 39(6), 1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine

Fie. 3 Back-scattered electron images of indium-containing minerals from Toyoha. 3-A: Rhythmic zoning in sphalerite from the Sorachi vein at -350 meter level. The brighter zones contain more in- dium and copper (roquesite mol) than the darker zones. Sphalerite covers more than 99 percent of the the area, which corresponds to those in Figs. 4-C and 4-D. 3-B: Zoning of the anisotropic chalcopyrite, stannite, presumable roquesite, and mixtures of their fine grains in the sample B409. Black part is the anisotropic chalcopyrite, gray part is stannite. The brightest white band (RQ) is presumably of roquesite. Central part of this picture corresponds to the areas shown in Figs. 4-A and 4-B. 3-C: A part of Fig. 3-B. Note the complex mixture of chalcopyrite (CP, black), stannite (ST, gray), and roquesite (RQ, white). 3-D: The anisotropic chalcopyrite in the same section with Figs. 3-B and 3-C. Bright white bands and dots are of stannite (ST). The fingerprint-like fine patterns on chalcopyrite (CP) is presumably due to heterogeneity of minor ele- ment distribution. 3-E: Paragenesis of roquesite, the Zn-In mineral and the solid solution between them from the Soya vein at -550 meter level. Note that the Zn-In mineral (ZI, gray) is in between roquesite (RQ, white) and sphalerite (SP, dark gray), and that roquesite is in direct contact with chalcopyrite (CP, black). The boundary of roquesite to the solid solution (RSS, light gray to gray) is gradational, while that to the Zn-In mineral is sharp. The area corresponds to that in Fig. 4-E. 3-F: Intergrowth of stannite (ST), the CP-ST ss (SS) and the anisotropic chalcopyrite (CP) from the Shinano vein at -450 meter level. The area corresponds to that in Fig. 4-F.

359 360 E. OHTA MINING GEOLOGY

Fig. 4 Compositional maps of indium-containing minerals from Toyoha. The weight percent scales in the figures are approximate ones. 4-A: Distribution of indium in the central area shown in Fig. 3-B. The red band is presumably of roquesite with mixtures of fine-grained chalcopyrite and stannite. Bands with intermediate indium contents are of stannite with mixtures possibly of chalcopyrite and roquesite. Darkest areas correspond to the anisotropic chalcopyrite. 4-B: Distribution of tin in the same area with Fig. 4-A. 4-C: Distribution of indium in sphalerite. The area corresponds to that in Fig. 3-A. 4-D: Distribution of copper in the same area with Fig. 4-C. Note the pattern is almost identical to that of indium. 4-E: Distribution of indium in the area corresponds to that in Fig. 3-E. Note the heterogeneity in the grains due to the solid solution (RSS, light brown to light blue) between the Zn-IN mineral (ZI, light blue at the upper and left fringes of roquesite) and roquesite (RQ, brown). 4-F: Distribution of tin in an aggregate of stannite (ST, yellow), the CP-ST ss (SS, light blue) and the anisotropic chalcopyrite (CP, dark blue). The red grain at the core is cassiterite (CS). The area corresponds to that in Fig. 3-F (turned about ninety degree). 39(6), 1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine 361 boundaries against them in some occasions, celerating voltage and sample current for the but in other occasions, the boundaries are al- quantitative analyses are 20 kV and 10 to 20 most invisible under microscope. In the latter nA on the MgO standard. Several points for case, the roquesite is actually a solid solution each mineral described below were qualita- with composition close to that of the Zn-In tively analyzed. Characteristic X-rays were mineral and sakuraiite as is described later. selected in accordance with the result, and Moreover, the colors of kesterite and sakurai- measured; CuKƒ¿, AgLƒ¿, FeKƒ¿, ZnKƒ¿, InLƒ¿, ite resemble that of the Zn-In mineral, and it is SnLƒ¿ and SKƒ¿ for all points; PbMƒ¿ for bern- essentially impossible to discriminate between dtite and herzenbergite; SbLƒ¿ and AsLƒ¿ for kesterite and sakuraiite under microscope, tetrahedrite; MnKƒ¿ and CdLƒ¿ for some because there is no distinct gap in chemistry points on sphalerite and the CP-ST ss, and between these minerals from Toyoha, like as ZAF-atomic number (Z), absorption (A) and those from the Ikuno mine (SHIMIzu et al. fluorescence (F)- corrections were made. 1986). Both roquesite and sakuraiite are weak- Standards are pure metals (for Ag, Cd, Mn, ly anisotropic, and show neither bireflectance Sb, Sri, and Zn), chalcopyrite (Cu, Fe, S), nor internal reflection. Thin layers possibly of galena (Pb), synthetic GaAs (As) and syn- roquesite mixed with extremely fine grains of thetic InP (In). Though a pure metal standard the anisotropic chalcopyrite and indium-rich of indium was used instead of InP for some of stannite (Figs. 3-B, 4-A, 4-B) are recognized the analyses, no significant difference in the also in a piece of drill core named B409-113.7 results is recognized. More than three hundred m (referred to as sample B409 in the following and seventy points have been analyzed in this text). Locality of the core corresponds to - 350 manner, and about three hundred data which meter level of the Shinano vein. It is notable total in the range of 100•}1 weight percent are that roquesite is observed only in chalcopyrite- employed in this report. However, additional rich ore, and generally in direct contact with ten data which do not total in the range are the Zn-In mineral, kesterite or chalcopyrite, also employed especially to make the diagrams but rarely with sphalerite (Fig. 3-E), while the because of their unique compositions. Zn-In mineral is widely distributed in sphal- Minerals containing indium as minor element: erite. This fact indicates that the assemblage BOORMANand ABBOTT(1967) present that roquesite-sphalerite is not stable at least in the weight percentages of indium in chalcopyrite, formation conditions of the Toyoha deposit. sphalerite and tetragonal stannite associated Cu-Zn-Fe mineral (substage B): with roquesite from Mount Pleasant, New This unnamed phase, newly found in this Brunswick, Canada is 0.19, 1.25 and 2.10 res- study, is recognized in a polished sample from pectively. PICOT and PIERROT(1963) describe -550 meter level of the Soya vein . This strong- the first occurrence of roquesite as inclusions ly anisotropic phase occurs as dendrites com- within bornite from the Charrier mine, France. pletely included within the anisotropic chal- They have revealed that maximum indium copyrite (Fig. 2-C) associated with roquesite, concentration of sphalerite inclusions in the kesterite, sakuraiite, sphalerite and the Zn-In bornite is 0.8 weight percent. Sphalerite from mineral. Its color is brownish gray with a vio- the Deputatskoe deposit, USSR, contains 0.31 let tint, and pleochroism is not recognized. weight percent indium at maximum (VLASOV, 1966). The minerals from Toyoha contain the Chemistry of Minerals same order or more of indium. Representative Analytical procedure: EPMA analysis data of chalcopyrite are listed Shimadzu EPMA-8705 (and its old model in Table 2. Though some points on the aniso- XMA-2 for some of the data) with X-ray take tropic chalcopyrite in the sample B409 appar- off angle 52.5 degrees has been employed to ently contain as much as three weight percent get chemical data and back-scattered electron indium, measured indium contents in chal- images of the indium-containing minerals. Ac- copyrite from other localities in Toyoha do 362 E. OHTA MINING GEOLOGY: Table2 Representativechemical compositions of chalcopyrite(CP) and the Cu-Zn-Fe (CZF) mineralfrom Toyoha. See Table 6 for abbreviations

Table 3 Representative chemical compositions of the Ag-In mineral (AI), hocartite (HC), berndtite (BD), herzenbergite (HZ), and rhodostannite (RS) from Toyoha. See Table 6 for other abbreviations

not exceed 0.4 weight percent. Such high in- weight percent indium and three weight per- dium contents in the former chalcopyrie may cent tin at their maximums. It is notable that be partly attributed to mixtures of extremely all data of the anisotropic chalcopyrite are fine-grained indium-rich stannite/kesterite plotted on the chalcopyrite-stannite tie line in and roquesite in chalcopyrite (Figs. 3-C, 3-D). Fig. 5. Representative chemical compositions However, careful checks of the sample B409 of hocartite and rhodostannite are shown in with high magnification back-scattered elect- Table 3. Maximum indium contents of hocar- ron images proved that chalcopyrite in the tite and rhodostannite are 0.14 (in 26 analyses) sample definitely contains more than one and 0.28 (4 analyses) weight percent respective- 39(6), 1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine 363

Fig. 5 Cu-Fe+Zn-In+Sn diagram of the CSR group minerals from Toyoha. Solid lines in the diagram are iso- value lines of observed In/In+Sn, and broken lines are of calculated In/In+Sn assuming that Fe+3 is zero. CP: chalcopyrite, SS: the CP-ST ss, ST: stannite, RQ: roquesite, ZI: Zn-In mineral, SP: sphalerite, CZF: Cu-Zn-Fe mineral. Small open circles by the abbreviations in the figure are at ideal compositions of corresponding phases. Addition of minor Ag to Cu and Mn+Cd to Fe+Zn does not make any recognizable difference on this diagram. Dots around the CZF mineral and chalcopyrite include data which exhibit less that 0.1 In+Sn in 8 total atoms. Though their In/ In+Sn are not necessarily in the range from 0.00 to 0.29, the ratio for those with such low In +Sn is beyond the scope of this discussion. CSR: chalcopyrite-sphalerite-roquesite. ly. The Ag/Cu+Ag atomic ratios in hocartite of CuS and FeS, because the observed max- are between 0.98 and 1.00. Toyohaite (YAJIMA imum solubility of copper in the sphalerite et al. in prep.), a newly confirmed silver phase between 300 and 500•Ž is only 1.6 analogue of rhodostannite, contains less than weight percent (SHIMA et al., 1982; KO.IIMA and 0.41 weight percent indium. Measured indium SUGAKI, 1984). concentrations in herzenbergite, berndtite, Ag-In mineral: teallite, and tetrahedrite from Toyoha are very The unnamed Ag-In mineral contains both low in general, and their maximum values are silver and indium as major components (Table 0.18 (in 8 analyses), 0.16 (6 analyses), 0.21 (12 3), and reveals chemical composition close to analyses), and 0.08 (78 analyses) weight per- AgInS2. Its Ag/Ag+Cu atomic ratios are be- cent respectively. As Table 2 shows, indium tween 0.96 and 0.98 (in 5 analyses). No contents in the Cu-Zn-Fe mineral are between crystallographical data for this mineral is 0.31 and 0.72 weight percent (5 analyses). obtained yet. However, those of synthetic Chemical compositions of the Cu-Zn-Fe min- AgInS2 is well documented (e.g. ROTHet al., eral are intermediate of chalcopyrite and sphal- 1973), and comparative study might be done erite, and close to 0.5CuFeS2+3(Zn, Fe)S, in the future. In chemical term, this is where the atomic ratios Fe/Zn in the sphaler- regarded as Ag analogue of roquesite. ite mol is approximately 0.1. This phase re- Zn-In mineral and sphalerite: sembles the cuprian sphalerite described by Normal sphalerite generally contains less CLARKand SILLITOE(1970), and is probably than 0.3 weight percent indium and optically a metastable phase which has exsolved from homogeneous, but indium sphalerite associ- the zinc-containing intermediate solid solution ated with the Zn-In mineral often shows rhyth- 364 E. OHTA MINING GEOLOGY:

Table 4 Representative chemical compositions of solid solution between sphalerite and the Zn-In mineral.

ZI:Zn-In.mineral and the solid solution with less than 50 percent sphalerite mol, SP:sphalerite and the solid solution with more than 50 percent sphalerite mol. See Table 6 for other abbreviations.

mic zoning easily recognizable under optical quesite or sphalerite. The synthetic CuZn21nS4 microscope. Distribution maps of copper and has sphalerite structure (PARTHEet al., 1969; indium in Figs. 4-C and 4-D evidently show KISSINand OWENS, 1986). However, weak that the zoning is due to these elements pro- anisotropism occasionally observed in the Zn- portionally distributed in sphalerite. Average In mineral is inconsistent with the cubic weight percentages of indium and copper in sphalerite structure. Therefore the structure of the mapped area are calculated to be 2.5 and the Zn-In mineral is not easily determined, 1.6 respectively. This gives Cu /In atomic ratio but is probably close to that of sphalerite. around 1.1, and is in good agreement with the Roquesite: quantitative analysis of indium sphalerite Representative analysis data of roquesite which are plotted to the upper side of the ro- (RQ) and its solid solution with the Zn-In quesite-sphalerite tie line in Fig. 5. As Table 4 mineral (ZI) are listed in Table 5. They are and Fig. 5 show, the solid solution between plotted to the stannite (ST) side of the ZI-RQ sphalerite and the Zn-In mineral seems to be tie line in Fig. 5. The zinc-rich end of the RQ- complete. An extensive solid solution is rec- ZI solid solution is close to sakuraiite which ognized also between roquesite and the Zn-In data are plotted to the roquesite side of the mineral. All these facts indicate that indium ST-ZI tie line. The range of the solid solution is very soluble in sphalerite as roquesite is from RQ90ZI10to RQ37ZI63when kesterite (CuInS2) mol, and that the crystal structure of mol is neglected. A wide variation in the com- the Zn-In mineral is similar to that of ro- position between RQ90ZI10 and RQ49ZI51 is 39(6), 1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine 365

Table 5 Representative chemical compositions of solid solutions among roquesite , kesterite and the Zn-In mineral from Toyoha.

RQ:roquesite and solid solutions between the Zn-In mineral and roquesite, KS:kesterite and solid solutions between the Zn-In mineral and kesterite (sakuraiite). See Table 6 for other abbreviations. recognized even within a single grain shown in the Zn-In mineral. Observed highest mol ratio Figs. 3-E and 4-E. The compositional gap of the Zn-In mineral to kesterite among them recognized between the solid solution and the is 70 to 30. Observed variation in Zn/Fe+Zn Zn-In mineral is indicated also by the sharp of stannite and kesterite from Toyoha is be- boundary between them on the back-scattered tween 0.09 and 0.94, and no definite gap is electron image (Fig. 3-E). Some data plotted recognized in it. Though stannite and kesterite at the midst of roquesite and stannite (Figs. 5, are structurally distinct (HALL et al., 1978), 8) are of the fine-grained mixtures in the sam- Zn/Fe+Zn atomic ratios can be high up to ple B409 (Fig. 3-C). The mixtures are 0.55 in stannite, and be as low as 0.45 in presumably of roquesite and indium-rich stan- kesterite (PETRUK, 1973). Consequently, nite or kesterite. chemical compositions are useless to Stannite, kesterite and sakuraiite: discriminate between the two if the ratio is in Results of the EPMA analyses of stannite the range from 0.45 to 0.55. Strict discrimina- and kesterite are shown in Tables 5 and 6. tion, however, is not needed in the following Sakuraiite can be considered as a solid solu- discussion, therefore the name 'kesterite' is tion of kesterite and the Zn-In mineral. Some used for those in which Zn/Fe+Zn are larger data which correspond to compositions of than 0.5. Weight percent range of indium con- sakuraiite are plotted between kesterite and tents in stannite is 0.04 to 9.85 for 25 points ex- 366 E. OHTA MINING GEOLOGY:

Table 6 Representative chemical compositions of stannite (ST), the CP-ST ss (SS), and the mixtures of fine- grained stannite/kesterite and roquesite (MKR) from Toyoha.

SR: Sorachi vein, IZ: Izumo vein, SN: Shinano vein , SY: southern Soya vein, B409 : the sample B409 (corresponds to -350 meter level of Shinano vein) . n.a.: not analyzed. Numbers immediately after the vein name abbreviations indicate levels (depth in meters). cept those in the sample B409, in which in- dium contents of the stannite bands (Figs. 3- Discussions B, 4-A, 4-C) reach up to 20.0 weight percent. Minerals as indium carriers: This may be partly attributed to evenly mixed Indium contents of herzenbergite, bern- roquesite and chalcopyrite grains; not to ro- dtite, teallite, rhodostannite, toyohaite, and quesite grains only, because even those points hocartite are low as already described, and the plotted to the chalcopyrite side of ST on Fig. 5 Ag-In mineral is quite rare. Therefore these contain as high as 14.5 weight percent indium . minerals are negligible as indium carriers in The indium content of kesterite ranges from economic sense. Probably more than 99 per- 0.11 to 1.86 weight percent (14 analyses) in the cent of indium in _,Toyoha is concentrated in Sorachi vein between -200 and -450 meter the Zn-In mineral, sphalerite, stannite, levels, and 5.90 to 16.51 (4 analyses) in the kesterite, sakuraiite, roquesite and the Soya vein at -550 meter level and in the sam- anisotropic chalcopyrite. As all of these ple B409. In/In+Sn atomic ratios also vary minerals and the Cu-Zn-Fe mineral are com- widely from 0.00 to 0.57. In short, kesterite , posed mainly of Cu, Fe, Zn, In, Sn and S, and sakuraiite and stannite associated with ro- plotted within the chalcopyrite-sphalerite-ro- quesite are very rich in indium, and are all plot- quesite triangle in Fig. 5, they are expressed as ted to the roquesite side of the ST-ZI tie line CSR group minerals in the following discus- on Fig. 5. sion. They have 1:1 metal to sulfur ratio, and 39(6), 1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine 367

Fig. 7 Histogram of calculated Fe+3 and calculated Fe+3+In+2Sn for the CSR group minerals. Ac- tually the latter equals to Cu+Ag. 1: normal chalcopyrite, 2: anisotropic chalcopyrite, 3: The Fig. 6 Histogram of total metal on the basis of, 8 CP-ST ss and the mixtures of stannite and the total atoms calculated from the analysis for the anisotropic chalcopyrite in the sampel B409, 4: in- CSR group minerals and hocartite. dium-rich stannite and kesterite in the sample B409, 5: the Cu-Zn-Fe mineral, 6: stannite, kesterite, roquesite, sphalerite and the Zn-In belong to tetragonal or cubic crystal system, mineral. The Fe+3+In+2Sn histogram is for only those with Fe+3 higher than 0.25. provided that the Zn-In mineral is either cubic or tetragonal as discussed in the preceding chapter. Valences of metals in these minerals ence is probably due to systematic error of the are considered to be + 1 for Cu and Ag, +2 analysis and the ZAF correction. for Zn, +3 for In, +4 for Sn, and +2 and Relation of Fe+3 and In, and element substitu- +3 for Fe (e.g. KATO, 1974). With this assump- tions in the CSR group minerals: tion, the ideal chemical formula common for Provided that the ideal formula is appli- the CSR group minerals is expressed as: cable to the CSR group minerals, following (Cu, Ag)m(Zn, Fe+2)d(In, Fe+3)tSnqS4. equations are obtained: Fig. 6 shows a histogram of total numbers of Cu+A2+Fe+2+Zn+Fe+3+In+Sn=4 the metals in the formula, m+d+t+q, for (m+d+t+q) 184 analyses of the CSR group minerals and Cu+Ag+2(Fe+2+Zn)+3(Fe+3+In)+4Sn hocartite. The average (4.04) is close to the =8 (total charge) theoretical number (4.00). The slight differ- therefore 368 E. OHIA MINING GEOLOGY:

Colc.Fe 3 (Cu+Ag-2Sn-In) Zn/Fe+Zn Fig. 8 Calculated Fe+3 vs. In diagram of the CSR Fig. 9 Zn/Fe+Zn vs. In/In+Sn (atomic ratios) group minerals. The Fe+3 axis corresponds to that diagram of the CSR group minerals with both In- in Fig. 7. Plus (+) marks data of the sample B409. +Sn and Fe+Zn value more than 0.1 (in 8 total Abbreviations are RQ: roquesite, ZI: Zn-In atoms). Plus (+) marks data of the sample B409. mineral, SP: sphalerite, ST: stannite, KS: kesteritei See Fig. 8 for abbreviations. CZF: Cu-Zn-Fe mineral, SS: CP-ST ss, CP: chalcopyrite, MCS: mixture of chalcopyrite and stannite in the sample B409, MKR: mixture of total atoms) indium, and Fe+3 is less than 0.25 kesterite/stannite and roquesite in the sample in the points which contain more than 0.1 of B409. indium. Based on the chemical analyses, these abnormal phases plotted between normal Fe+3=Cu+Ag-2Sn-In chalcopyrite and roquesite on the Figs. 5 and 7 Fig. 7 shows a histogram of Fe+3 for these are attributed to three types of substitutions. minerals calculated by means of this equation. For the phases plotted between normal As is expected, the data for stannite, kesterite, chalcopyrite and stannite on Fig. 5, the sphalerite, roquesite, and the Zn-In mineral substitution of (Fe +2, Zn)Sn for 2Fe+3 is domi- make a sharp peak at 0.0 Fe+3, and data of op- nant, and the substitution of In for Fe+3 is im- tically normal chalcopyrite concentrate at 2.0 portant only to the indium-rich stannite. A Fe+3. The anisotropic chalcopyrite exhibits combination of the two, the substitution of Fe+3 between 1.65 and 1.95, the Cu-Zn-Fe (Fe, Zn)Sn for 21n, causes the indium-rich mineral between 0.25 and 0.55, and two data stannite and kesterite plotted between normal of anomalously indium-rich stannite and stannite and roquesite. As for the In/In+Sn kesterite in the sample B409 between 0.25 and atomic ratio, following equation is obtained 0.35. The ranges for the CP-ST ss and for the from the above equations: mixtures of stannite and chalcopyrite in the rc=2c+Fe+3-m sample B409 are almost same; between 0.35 where r is In/Sn+ln, and c represents total and 0.75. Fig. 7 shows also that minerals with number of tin and indium in eight total atoms. Fe+3 higher than 0.25 except the Cu-Zn-Fe As shown in Figs. 7 and 8, Fe+3 is essentially mineral make a peak at 2.0 of Fe+3+In+2Sn, zero for the majority of those with high in- which is identical to Cu+Ag. In addition to dium contents. If Fe+3 equals zero: this fact, Fig. 8 clearly shows that indium is in- r=1-m/c compatible with Fe+3 in all samples except the From this equation, iso-r lines for Fe +3=0 are B409; the analyzed points with the calculated put in Fig. 5, which shows that observed iso-r Fe +3 more than 0.25 contain less than 0.1 (in 8 lines are plotted slightly to the left of the 39(6), 1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine 369 calculated lines of the same r value. This may a sample from the Sorachi vein at -350 meter be attributed to the existence of minor level. amounts of Fe+3, Mn+3 etc., as well as to the 310(242), 350(315) and 358(331)•Ž; using analytical error. A diagram of In/In+Sn ver- three pairs of sphalerite and kesterite in con- sus Zn/Zn+Fe for the CSR group minerals tact with each other in a sample from the Soya shows positive correlation of the ratios (Fig. 9). vein at - 550 meter level.

Those data of the sample B409 are out of the The values within parentheses are calculated trend here again. The solid solutions between from the equation after NEKRASOV et al. (1979), sphalerite and roquesite through the Zn-In and those without are after NAKAMURA and mineral are due mainly to a substitution of SHIMA (1982). The equations are applied only 2(Zn, Fe) for Culn. The substitution of (Zn, topairs where the grains show fairly homoge- Fe)In for CuSn recognized between kesterite neous'Zn/Fe+Zn ratios, and do not contain and sakuraiite from the Ikuno mine (SHIMIZU much elements, such as indium, which are not et al., 1986) is deduced from the two substitu- in the experimented system. The equation of tions already discussed, (Zn, Fe)Sn for 21n NEKRASOV et al. gives unreasonably low tem- and 2(Zn, Fe) for CuIn. This substitution is perature for the pair from the Shinano vein, recognized also in Toyoha. Obviously, a and, therefore, that of NAKAMURA and SHIMA substitution of CuFe+3 for 2(Zn, Fe+2) in should be employed here. Such small number sphalerite make the Cu-Zn-Fe mineral. The of data can not be representatives of averaged compositional deviations of stannite and the formation temperatures of the veins by any CP-ST ss towards sphalerite (Fig. 5) may be means, but suggest that peak temperatures due to influence of adjoining sphalerite were significantly higher than 300•Ž at the sub- around their boundaries, or may indicate solid stage of tin-indium mineralization. solutions between them. This should be left to Phases as evidences for high formation further studies. temperatures: Estimation of equilibrium temperatures of The concentric parallel bands of indium- sphalerite and stannite/kesterite: containing chalcopyrite, indium-rich stan- YAJIMA and OHTA (1979) estimated the for- nite/kesterite, roquesite and mixtures of their mation temperature range of the Izumo vein extremely fine grains (Figs. 3-B, 3-C, 3-D) in at 200 to 300•Ž through fluid inclusion work. the sample B409 can not simply be considered However, the fluid inclusion temperatures as normal aggregates of these minerals. All the were measured only for coarse crystals of analysis data of these minerals and their mix- quartz and of translucent sphalerite. Both of tures are plotted on the chalcopyrite-roquesite them are rather rare in the later-stage veins, tie line in Fig. 5, which is consistent with the and there is no evidence that the formation microscopic observation that even a piece of temperatures of other minerals are in the same other mineral is not recognized in these bands. range. With this point of view, equilibrium Besides, the mixtures are not recognized in nor- temperatures for some pairs of sphalerite and mal stannite nor in normal chalcopyrite. stannite or kesterite are calculated from their These features indicate that the mixture in Fig. compositions by means of the Fe-Zn partition- 3-C is not a product of precipitation of such ing equations under the assumption that the fine-grained minerals nor of replacement. equations are applicable also to the kesterite- Therefore, the formation of the mixture might sphalerite pair. The results are: be attributed to exsolution of a series of zoned 228(118)•Ž; using averaged compositions of intermediate solid solutions between indium- sphalerite (8 points) and stannite (6 points) in rich stannite and chalcopyrite, and between a sample from the Shinano vein at -450 meter stannite/kesterite and roquesite. Though ex- level. istence of a wide-range solid solution of the lat- 352(319)•Ž; using averaged compositions of ter pair has not been reported yet, the abnor- sphalerite (4 points) and kasterite (8 points) in mal data of the mixtures in the sample B409 370 E. GHTA MINING GEOLOGY:

plotted in Figs. 8 and 9 indicate that wide- the Zn-In mineral. Observed continuous solid range solid solutions exist between CuFeS2 solutions between RQ90ZI10and RQ37ZI63ibe-

and CuInS2 by the combined substitutions of tween KS100ZI0and KS30ZI70, and between In for Fe+3 and of 2Fe+3 for (Fe+2, Zn)Sn. ZI100SP0and ZI0SP100are attributed to coupl- Some data for indium-rich stannite and ed substitutions of 2(Zn, Fe) for CuIn and of kesterite plotted to the right of normal stan- (Zn, Fe)In for CuSn. Other dominant substitu- nite composition in Fig. 5 are consistent to this tions recognized are of (Fe+2, Zn)Sn for hypothesis. Experimental data for the chalco- 2Fe+3 between chalcopyrite and stannite, and

pyrite-stannite solid solutions (OHTSUKI et al., of (Fe+2, Zn)Sn for 21n between stannite/ 1980, 1982) show that an assemblage of tin- kesterite and roquesite.

poor stannite and an intermediate solid solu- (3) Though indium is incompatible with tion is stable in sulfur-poor conditions at Fe+3 in the CSR group minerals, the texture 400•Ž. Tin contents of the stannite are as low and chemical compositions of the mixtures of as 11 atomic percent (Sn 0.88 in 8 total atoms), the anisotropic chalcopyrite, indium-rich stan- and of the solid solution are I to 3.3 atomic nite/kesterite, and roquesite in the sample

percent (Sn 0.08 to 0.26). They may corres- B409 indicate wide-range substitution of In

pond to the CP-ST ss and the anisotropic for Fe+3 at high temperatures. Therefore high chalcopyrite assemblage. In any case, the CP- indium contents in such mixtures and asso- ST ss suggests that a pulse of high temperature ciated chalcopyrite are expected at deep levels may have reached up to 400•Ž in the later- of the southeastern later-stage veins. stage veins which have been formed under (4) The occurrences of the Zn-In mineral sulfur-poor conditions as is evidenced by the and of roquesite indicate that the assemblage mineral assemblages (YAJIMA and OHTA, 1979; roquesite-sphalerite is unstable at least in the OHTA, 1980). Various types of rhythmic zon- formation conditions of the Toyoha deposit.

ings are commonly recognized in the later- (5) The later-stage veins are considered to stage veins; for various assemblages of min- have been formed by pulsatile mineralization erals, for indium, copper and iron contents in whose peak temperatures were 50 to 100•Ž sphalerite, for cobalt contents in pyrite and higher than the hitherto estimated maximum arsenopyrite (OHTA, unpublished), for As/Sb formation temperature (300•Ž) of the Toyoha

ratios in tetrahedrite-tennantite solid solution deposit. etc. These zonings, together with the Acknowledgments: The author is grateful to discrepancy between the fluid inclusion data Dr. J. YAJIMA,Hokkaido Branch Office of the and the Fe-Zn partitioning temperatures, sug- Geological Survey of Japan for his extensive gest that the later-stage veis have been formed cooperation on the subject and advice on by pulsatile mineralization which peak temper- the manuscript. The polished sections for the atures were high enough to form the solid so- EPMA analyses were provided by Messrs. S. lutions and the mixtures described above. WATANABE,T. KIMURAand T. SATOin the same office. Also he would like to acknowledge Conclusions Messrs. K. KuMITAand H. KANBARAof the On the basis of the above results and discus- Toyoha Mining Company for their help for sions, it is concluded that: the underground survey and sample collec- (1) Economically most important indium car- tion. riers in the Toyoha deposit are the Zn-In mineral and indium sphalerite distributed in References the later-stage veins. Next important are kes- AKOME,K. and HAKAGUCHI,M. (1963) : Geology and ore terite, stannite and the anisotropic chalcopy- deposits of Toyoha mine. Mining Geol., 13, 93-99 rite. (in Japanese with English abstract). (2) The indium sphalerite is proved to be a AKOME,K. and HARAGUCHI,M. (1967) : The characteristics solid solution between normal sphalerite and of fracture and mineralization of the Toyoha mine. 39(6),1989 Occurrence and chemistry of indium-containing minerals from the Toyoha mine 371

Mining Geol., 17, 93•`100 (in Japanese with English exploration results at the Toyoha polymetallic vein-

abstract). type deposits, Hokkaido, Japan. Mining Geol., 38,

BOORMAN, R. S. and ABBOTT, D. (1967) : Indium in coex- 99•`113 (in Japanese with English abstract).

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Can. Mineral., 9, 166•`179. and development of the Toyoha area. 1156p (in

CLARK, A. H. and SILLITOE, R. H. (1970) : Cuprian Japanese).

sphalerite and a probable copper-zinc sulfide, NEKRASOV, I. J., SOROKIN, V. I. and OSADCHII, E. G. (1979) :

Cachiyuyo de Llampos, Copiapo, Chile. Am. Fe and Zn partitioning between stannite and

Mineral., 55, 1021•`1025. sphalerite and its application in geothermometry. In

HALL, S. R., SZYMANSKI, J. T. and STEWART, J. W. (1978) : Origin and Distribution of the Elements, L. H.

Kesterite, Cu2(Zn, Fe)SnS4, and stannite, Cu2(Fe, AHRENS, ed., Pergamon Press, 739•`742.

Zn)SnS4, structually similar but distinct minerals. OHTA, E. and YAJIMA, J. (1979): New occurrence of

Can. Mineral., 16, 131•`137. canfieldite and berthierite from the Toyoha mine

HASHIMOTO, H., ISHIZAKA, T. and ICHINOSE, T. (1977) : Re- (abstract). Abst. Joint Meet. Soc. Mining Geol.

cent exploration for the Izumo vein of the Toyoha Japan, Mineral. Soc. Japan, and Japan Assoc.

mine. Mining Geol., 27, 87•`97 (in Japanese with Mineral. Petrol. Econ. Geol., p. 96 (in Japanese).

English abstract). OHTA, E. (1980) : Mineralization of Izumo and Sorachi

JOHAN, Z. *and PICOT, P. (1982) : Pirquitasite, a new veins of the Toyoha mine, Hokkaido, Japan. Bull.

member of the stannite group. Bull. Mineral., 105, Geol. Stirv. Japan, 31, 585•`597 (in Japanese with

229•`235 (in French with English abstract). English abstract).

KANBARA, H., SANGA, T., OHURA, T. and KUMITA, K. OHTA, E. and MARUMO, K. (1985) : Occurrence of apatite

(1989) : Mineralization of Shinano vein in Toyoha and associated gangue minerals in the Toyoha deposits, west Hokkaido, Japan. Proc. Japan polymetallic vein-type deposits, Hokkaido, Japan. Mining Geol. 39, 107•`122 (in Japanese with English Academy, 61, Ser. B, 99•`102.

abstract). OHTA, E., YAJIMA, J. and KANAZAWA, Y. (1987) :

KASE, K. (1987) : Tin-bearing chalcopyrite from the Izumo Chemistry of ore minerals from the Toyoha mine

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. Mineral., 25, 9•`13. Japan, Mineral. Soc. Japan, and Japan Assoc.

KATO, A. (1974) : Sulphide minerals in the Cu-(Fe, Zn)- Mineral. Petrol. Econ. Geol., p. 68 (in Japanese).

(Sn, In) system. Jour. Mineral. Soc. Japan., 11, OHTSUKI, T., KITAKAZE, A. and SUGAKI, A. (1980) : Syn-

Spec. Iss. No. 2, 145•`153 (in Japanese). thetic minerals with quaternary components in the

KISSIN, S. A. and OWENS, D. R. (1986) : The system Cu-Fe-Sn-S-Synthetic sulfide minerals (X)-Sci. crystallography of sakuraiite. Can. Mineral., 24, Rept. Tohoku Univ. Ser. 3, 14, 269•`282.

679•`683. OHTSUKI, T., SUGAKI, A. and KITAKAZE, A. (1982) : Study

KOJIMA, S. and SUGAKI, A. (1985) : Phase relations in the on phase relations of Cu-Fe-Sn-S system (V)

Cu-Fe-Zn-S system between 500•Ž and 300•Ž (abstract). Abst. Joint Meet. Soc. Mining Geol.

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158•`171. Mineral. Petrol. Econ. Geol., p. 171 (in Japanese).

KOJIMA, S., KAWAZUMI, T., TAKEYAMA, T. and MIYAISHI, PARTHE, E., YVON, K. and DEITCH, R. H. (1969) : The

O. (1979) : The modes of occurrence and mineralogy crystal structure of Cu2CdGeS4 and other quaternary

of silver minerals from the Toyoha Mine. Mining normal tetrahedral structure compounds. Acta Cryst.

Geol., 29, 197•`206 (in Japanese with English B25, 1164•`1174.

abstract). PETRUK, W. (1973) : Tin sulfides from the deposit of

MIYAJIMA, T., HAKARI, N. and KITA, M. (1971) : Some con- Brunswick Tin Mines Limited. Can. Mineral. 12,

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22•`35 (in Japanese with English abstract). mineral d'indium: CuInS2. Bull. Soc. Franc. Miner.

NAKAMURA, Y. and SHIMA, H. (1982) : Fe and Zn partition- Crist. LXXXVI, 7•`14 (in French).

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Japan, and Japan Assoc. Mineral. Petrol. Econ. 8, 333•`338. SAWAI, O. and ITAYA, T. (1989) : K-Ar ages of sericite in Geol., A-8 (in Japanese). NARUI, E., YOSHIE, T. and KATO, K. (1988): On the recent hydrothermally altered rocks around the Toyoha 372 E. OHTA MINING GEOLOGY:

deposits, Hokkaido, Japan. Mining Geol., 39, UYTENBOGAARDT,W. and BURKE,E. A. J. (1971): Tables 191•`204. for Microscopic Identification of Ore Minerals. SHIMA, H., UENO, H. and NAKAMURA, Y. (1982) : Synthesis Elsevier Publishing Co., Amsterdam. 430p. and phase studies on sphalerite solid solution-the VLASOV,K. A. (1966) ed.: Genetic Types of Rare-Element systems Cu-Fe-Zn-S and Mn-Fe-Zn-S. Jour. Japan Deposits. Israel Program for Scientific Translations, Assoc. Miner. Petro. Econ. Geol., Spec. Iss. 3, 916p.

271•`280 (in Japanese with English abstract). WIGGINS, L. B. and CRAIG, J. R. (1980) : Reconnaissance

SHIMIZU, M., KATO, A. and SHIOZAWA, T. (1986) : of the Cu-Fe-Zn-S system: sphalerite phase relation-

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Fe)In-for-CuSn substitution. Can. Mineral., 24, YAJIMA, J. (1977) : New occurrence of tin-minerals from

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minerals de Pb-Zn de la province polymetallique des and formation process of the Toyoha deposits, Hok-

Andes du Perou Central. Mineral. Deposita, 22, kaido. Japan. Minine Geol.. 29. 291•`306.

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English abstract).

豊 羽 鉱 山 に おけ る イ ンジ ウム鉱物 の産 状 と化 学組 成

太田英順

要 旨:豊 羽銀 鉛亜 鉛 鉱 床 に は 錫 ・銅 と共 に イ ンジ ウム が ム 鉱 物 と 閃 亜 鉛 鉱 の 固 溶 体 で あ る こ と が 判 明 し た.ま

存 在 す る.ビ ス マ ス,タ ン グ ス テ ソ,ア ンチ モ ン,砒 た,イン ジ ウ ム 銅 鉱 と亜 鉛 イン ジ ウ ム鉱 物,ケ ス テ ラ イ

素,コ パ ル トも微量 な が ら広 範 囲 に分 布 す る.イン ジ ウ トと 亜 鉛 イ ン ジ ウ ム 鉱 物 そ れ ぞ れ の 間 に も 広 い 固 溶 体 の

ム鉱 物 と して は 閃亜 鉛 鉱 とイ ンジ ウム銅 鉱 の中 間 組 成 を 存 在 が 認 め ら れ た.こ れ ら の 固 溶 体 は2(Zn, Fe)と

有 す る亜 鉛 イ ン ジ ウ ム鉱 物,AgInS2の 組 成 を 有 す る 銀 CuIn,(Zn, Fe)InとCuSnの 置 換 に よ る も の で あ る.黄

イン ジ ウム鉱 物,イ ンジ ウ ム銅 鉱,櫻 井 鉱 が 産 す るが, 銅 鉱 と 黄 錫 鉱 間 の 固 溶 体 で は(Fe+2, Zn)Snと2Fe+3,

ケ ス テ ラ イ ト,黄 錫 鉱,閃 亜 鉛 鉱 ,異 方 性 を 有 す る黄 銅 黄 錫 鉱 ま た は ケ ス テ ラ イ ト と イ ン ジ ウ ム 銅 鉱 間 で は

鉱 もか な りの 量 の イ ン ジ ウ ムを 含 む,こ れ らの うち経 済 (Fe+z, Zn)Snと2Inの 置 換 が そ れ ぞ れ 主 な も の で あ る. 的 に 最 も重 要 な の は 亜 鉛 イ ン ジ ウ ム鉱 物 と含 イ ン ジ ウ ム 上 記 の 鉱 物 の 産 状 は,今 ま で 見 積 ら れ て い た 豊 羽 鉱 床 の

閃亜 鉛 鉱 で,次 い で ケス テ ライ ト,黄 錫鉱,含 イン ジ ウ 最 高 生 成 温 度(300℃)よ り も50か ら100℃ 高 い 温 度 で こ

ム黄 銅 鉱 で あ る.含 イ ン ジ ウ ム閃亜 鉛鉱 は亜 鉛 イ ンジ ウ れ ら の 鉱 物 が 晶 出 し た こ と を 裏 付 け る.