A New Zincian Greenockite Occurrence in the Saishitang Cu Skarn Deposit , Qinghai Province , Northwest China

Zn-Cd-S series minerals not only comprise industrial resources for Zn and Cd, but are also significant mineralogical indicators for hydrothermal ore-forming processes. Due to its unique formation conditions and rare occurrence, our understanding of the formation of zincian greenockite in natural systems is limited. Zincian greenockite was discovered during mineralogical studies in the Saishitang Cu skarn deposit, Qinghai Province, Northwest China. This provided an ideal opportunity to assess the occurrence and formation of zincian greenockite in skarn-type deposits. Ore minerals were observed using reflected-light microscopy, and the zincian greenockite was further analyzed using electron-probe microanalysis (EPMA) and X-ray diffraction (XRD). The zincian greenockite occurs in the bornite–chalcopyrite ores and is composed of subhedral to anhedral grains approximately 50 × 150 μm2 to 200 × 300 μm2 in size, replaces the bornite, and is replaced by native silver. Two phases (I and II) were identified based on back-scattered electron images, X-ray element-distributions maps, and EPMA data. The textural relationship indicated that Phase I was replaced by Phase II. Phase I contained high Zn (14.6 to 21.7 mol % ZnS) and low Cd (72.4 to 82.2 mol % CdS), while Phase II contained low Zn (5.6 to 9.1 mol % ZnS) and high Cd (85.4 to 89.9 mol % CdS). The zincian greenockite was formed at temperature of 300~270 ◦C during the transformation from a reducing environment to an oxidizing one in the late stage of the mineralization process in the Saishitang deposit.


Introduction
The Zn-Cd-S component system is of theoretical and practical significance for mineralogy and materials science [1][2][3].There are two structure types (cubic and hexagonal) for this system; the end members of ZnS and CdS are sphalerite and wurtzite, and hawleyite and greenockite, respectively.Sphalerite is one of the most common ore minerals, while wurtzite and greenockite are much less abundant, and hawleyite is rare [2].Experimental studies of the system ZnS-CdS have indicated the existence of a complete solid solution at temperatures above 600 • C [4][5][6][7][8][9][10].It has been shown that the solid solution exists to an extent at hydrothermal conditions below 400 • C [4], and that the replacement of Cd by Zn is a rather complicated process that is dependent on the formation environment [11].
The Saishitang deposit is an important deposit with metal reserves of 0.43 Mt Cu [25] in Qinghai Province, Northwest China.The deposit is hosted in stratiform skarn, which contains 1468 t of Cd, last evaluated in 1980s [25].Zincian greenockite was previously discovered during critical metals studies [26].This provides a good opportunity to assess how the zincian greenockite was formed during the mineralization processes of skarn deposits.In this paper, mineralogical investigations for ores of the Saishitang Cu deposit were first performed, after which the mineral chemistry and unit-cell parameters of the zinc greenockite were obtained.Finally, the forming conditions of the zincian greenockite were discussed.

Regional Geology of the Elashan Region
The Saishitang deposit is situated in the Elashan Metallogenic Belt (EMB) [27], Qinghai Province, Northwest China (Figure 1a).Geodynamically, the EMB is located in the junction between the western Qinling orogenic belt and eastern Kunlun orogenic belt [28,29].The lithologies of the EMB are composed of the Paleoproterozoic Jingshuikou Group gneisses, Ordovician to Carboniferous volcanic and carbonate rocks, Lower Permian carbonate and clastic rocks, Triassic carbonate and volcaniclastic rocks, and Neogene glutenite and Quaternary soil (Figure 1b).
The EMB experienced multiple periods of granitic magmatism from the Proterozoic to Early Mesozoic (Figure 1b) [30].The dominant periods are marked by Ordovician-Silurian (Variscan) and Permian-Triassic (Indosinian) units [28,30,31], with Late Triassic granites [30] being most abundant in the EMB.The Late Triassic granitites are I-type granites with minor A-type granites, which are believed to have been generated during the post-collision orogenic stage [31,32].orogenic Au deposits [23] and epithermal Au-Ag deposits [4,24].Its existence is yet to be reported in skarn deposits.
The Saishitang deposit is an important deposit with metal reserves of 0.43 Mt Cu [25] in Qinghai Province, Northwest China.The deposit is hosted in stratiform skarn, which contains 1468 t of Cd, last evaluated in 1980s [25].Zincian greenockite was previously discovered during critical metals studies [26].This provides a good opportunity to assess how the zincian greenockite was formed during the mineralization processes of skarn deposits.In this paper, mineralogical investigations for ores of the Saishitang Cu deposit were first performed, after which the mineral chemistry and unit-cell parameters of the zinc greenockite were obtained.Finally, the forming conditions of the zincian greenockite were discussed.

Regional Geology of the Elashan Region
The Saishitang deposit is situated in the Elashan Metallogenic Belt (EMB) [27], Qinghai Province, Northwest China (Figure 1a).Geodynamically, the EMB is located in the junction between the western Qinling orogenic belt and eastern Kunlun orogenic belt [28,29].The lithologies of the EMB are composed of the Paleoproterozoic Jingshuikou Group gneisses, Ordovician to Carboniferous volcanic and carbonate rocks, Lower Permian carbonate and clastic rocks, Triassic carbonate and volcaniclastic rocks, and Neogene glutenite and Quaternary soil (Figure 1b).
The EMB experienced multiple periods of granitic magmatism from the Proterozoic to Early Mesozoic (Figure 1b) [30].The dominant periods are marked by Ordovician-Silurian (Variscan) and Permian-Triassic (Indosinian) units [28,30,31], with Late Triassic granites [30] being most abundant in the EMB.The Late Triassic granitites are I-type granites with minor A-type granites, which are believed to have been generated during the post-collision orogenic stage [31,32].A large number of Cu-polymetallic skarn, Fe-polymetallic skarn, and orogenic Au deposits (Figure 1b) in the EMB are related to the Late Triassic granites [34].Cu-polymetallic skarn deposits are distributed east of the Elashan region, particularly in the Saishitang-Rilonggou orefield [26,29,35] which is the most important Cu mineralization area in Qinghai, or even in China [35].Among these deposits, the Saishitang Cu deposit is a well-developed and studied deposit [26][27][28][29]36,37], and furthermore, constitutes a typical skarn Cu deposit example for understanding mineralization in the Elashan region.A large number of Cu-polymetallic skarn, Fe-polymetallic skarn, and orogenic Au deposits (Figure 1b) in the EMB are related to the Late Triassic granites [34].Cu-polymetallic skarn deposits are distributed east of the Elashan region, particularly in the Saishitang-Rilonggou orefield [26,29,35] which is the most important Cu mineralization area in Qinghai, or even in China [35].Among these deposits, the Saishitang Cu deposit is a well-developed and studied deposit [26][27][28][29]36,37], and furthermore, constitutes a typical skarn Cu deposit example for understanding mineralization in the Elashan region.

Stratigraphy
The stratigraphy of the Saishitang deposit consists mainly of a Lower Permian series that underwent extensive regional metamorphism (also regarded as the Middle-Lower Triassic by some researchers [28]) overlain by Paleogene-Neogene and Quaternary covers (Figure 1b), as well as a slice of Proterozoic high-grade metamorphosed rock [26,29].The ore-bearing stratum of the Saishitang deposit constitutes Group C of the Lower Permian series [26].Skarn and ore bodies occur mainly in the contact between intrusions, metamorphosed tuff, and marble-containing metamorphosed siltstone [28].

Intrusive Rocks
The complex intrusions of the Saishitang deposit outcrop on a northwest-southeast (NW-SE) strike and are 3.5 km long and 0.5-1 km wide.Five intrusions were previously outlined (named I, II, III, IV, V) [38].The intrusions are complex, comprising five stages (stages A, B, C, D, E), and were identified based on crosscutting relationships and petrologic features.Stage A consists of diorite dykes distributed in the west of the No. III intrusion.Stage B constitutes medium-grained quartz diorite distributed in intrusions I and IV.Stage C is composed of fine-grained quartz diorite, plagioclase granite, and granodiorite porphyry, and is distributed in intrusions II and III.Stage D constitutes intermediate-felsic dykes, and Stage E is composed of felsic dykes [38].According to the alteration features, Stages A and B are pre-mineralization intrusions; Stage C is a syn-mineralization intrusion, and Stages D and E are post-mineralization intrusions.Geochemical and mineralogical features indicate that the intrusions are I-type granites [28].The Hf isotope data indicates that the intrusions of the Saishitang deposit originated from the partial melting of Mesoproterozoic lower crustal materials with the involvement of mantle-derived magmas [28].The zircon U-Pb ages of the quartz diorite yielded an estimate of 223-220 Ma, suggesting that they were emplaced in the Late Triassic [26,39].
The hydrothermal period can be divided into four stages.Stage III is characterized by the precipitation of the magnetite, replacing the garnet (Figure 5a).Minerals formed at Stage IV mostly include pyrite and chalcopyrite, bornite (Figure 5b), and pyrrhotite.The cobaltite is euhedral-subhedral, and is replaced by chalcopyrite and tetrahedrite (Figure 5c,d).The bornite is replaced by chalcopyrite and tetrahedrite (Figure 5c), while the chalcopyrite shows a leaf-like texture in the bornite (Figure 5g) or replaced bornite (Figure 5c).Minerals formed at Stage V include sphalerite, stannoidite, galena, actinolite, and quartz.Stannoidite replaces the bornite (Figure 5h).Minerals formed at Stage VI include wittichenite, stromeyerite, zincian greenockite, native silver, native bismuth, quartz, and calcite.Wittichenite and stromeyerite fill the fractures of the bornite, and the native silver and native bismuth replace the stromeyerite (Figure 5e,f).The detailed texture of the zincian greenockite is described in Section 4.1.The skarn period is characterized by the precipitation of anhydrous skarn minerals such as grossular-andradite garnet [41], diopside, and wollastonite (Stage I), which are replaced by the hydrous skarn minerals, such as amphibole and epidote (Stage II).
The hydrothermal period can be divided into four stages.Stage III is characterized by the precipitation of the magnetite, replacing the garnet (Figure 5a).Minerals formed at Stage IV mostly include pyrite and chalcopyrite, bornite (Figure 5b), and pyrrhotite.The cobaltite is euhedral-subhedral, and is replaced by chalcopyrite and tetrahedrite (Figure 5c,d).The bornite is replaced by chalcopyrite and tetrahedrite (Figure 5c), while the chalcopyrite shows a leaf-like texture in the bornite (Figure 5g) or replaced bornite (Figure 5c).Minerals formed at Stage V include sphalerite, stannoidite, galena, actinolite, and quartz.Stannoidite replaces the bornite (Figure 5h).Minerals formed at Stage VI include wittichenite, stromeyerite, zincian greenockite, native silver, native bismuth, quartz, and calcite.Wittichenite and stromeyerite fill the fractures of the bornite, and the native silver and native bismuth replace the stromeyerite (Figure 5e,f).The detailed texture of the zincian greenockite is described in Section 4.1.

Sampling Site
In our previous study [26], 19 ore samples were collected from 3400, 3350, 3300, and 3250 m above sea level (a.s.l) from underground workings and ores stores of the Saishitang deposit.The bornite-chalcopyrite ores that contain zincian greenockite were obtained from Line 19 at 3300 m a.s.l, and Line 18 at 3350 m a.s.l.

Electron-Probe Microanalyses
The ore minerals and textures were identified in polished thick sections using standard reflected-light microscopy techniques.The mineral chemical compositions and X-ray mapping were analyzed using a Shimadzu EPMA-1720H (Tokyo, Japan) electron probe micro-analyzer (EPMA) housed at the School of Geosciences and Info-physics (SGI), Central South University (CSU), Changsha, China.The operating conditions of the electron microprobe included a 15 kV accelerating voltage, 10 nA beam current, and 1 µm diameter electron beam.The X-ray lines used to analyze the different elements were as follows: S (Kα), Mn (Kα), Fe (Kα), Cu (Kα), Zn (Kα), Ag (Lα), and Cd (Lα).The mineral and metal standards used for elemental calibration included pyrite (S), metallic Mn (Mn), pyrite (Fe), chalcopyrite (Cu), sphalerite (Zn), argentite (Ag), and greenockite (Cd).The resulting data were processed by the atomic number (Z), absorption (A) and fluorescence (F) effects (ZAF) correction method using proprietary Shimadzu software.

X-ray Diffraction Analysis
X-ray diffraction (XRD) analysis was performed with a Rigaku D/Max Rapid IIR microdiffractometer (Rigaku Corporation, Tokyo, Japan) at 40 kV and 250 mA, using a Cu tube and a 0.05 mm collimator with 20 min exposure.The XRD raw data were processed using Jade 6.0 software, and recorded from 20 • to 60 • 2θ.The peaks were matched using the Powder Diffraction File (PDF) of the International Centre for Diffraction Data.The XRD analysis was completed at the SGI, CSU, Changsha, China.

Optical Properties and Textural Relations for Zincian Greenockite
In reflected light micrographs, zincian greenockite featured as dark grey, with low reflectance (but higher than sphalerite), weak anisotropism, and salmon to yellow internal reflection.Zincian greenockite was harder than bornite (Figure 6a) and the grains were subhedral to anhedral (Figure 6), approximately 50 × 150 µm 2 to 200 × 300 µm 2 , and occurred on the edges of the chalcopyrite, quartz, and calcite.Texturally, the bornite was replaced by the zincian greenockite later than the actinolite, which was replaced by the native silver (Figure 6).

Zincian Greenockite
A total of 30 spots were analyzed on six grains (No.: k31a5, k31a6, k31b, k31.6, k31b.15, and k31b.16;Table 1) of two samples (k31a, and k31b).The spots were selected with the assistance of X-ray maps.Examples of the Zn and Cd X-ray maps of the single grains are provided in Figure 7.
Zincian greenockite contained 62.53 to 72.66 wt % Cd, 2.66 to 10.88 wt % Zn, and 22.77 to 25.05 wt % S, with small amounts of Cu (0.06 to 2.39 wt %) and Fe (0.07 to 0.76 wt %), as well as traces of  7a); (d) zincian greenockite at the contact between bornite and actinolite (the detailed BSE image can be observed in Figure 7b); (e) zincian greenockite with wittichenite (Wtc) filling and replacing the bornite; (f) zincian greenockite filling in the fractures of bornite, and its association with calcite (Cal).

Zincian Greenockite
A total of 30 spots were analyzed on six grains (No.: k31a5, k31a6, k31b, k31.6, k31b.15, and k31b.16;Table 1) of two samples (k31a, and k31b).The spots were selected with the assistance of X-ray maps.Examples of the Zn and Cd X-ray maps of the single grains are provided in Figure 7.

XRD Data of Zinc Greenockite
The largest zinc greenockite grains (Figure 6f) were measured and the XRD patterns are indicated in Figure 10, while the peak data are provided in Table 4.The peak data patterns were in accordance with those of zincian greenockite from the International Centre for Diffraction Data (ICDD) PDF No. 40-0835, suggesting the zinc greenockite of the Saishitang deposit is hexagonal.In comparison to No. 40-0835, the unit-cell data of the zinc greenockite of the Saishitang deposit had a smaller a parameter, but a larger c parameter and cell volume V.

XRD Data of Zinc Greenockite
The largest zinc greenockite grains (Figure 6f) were measured and the XRD patterns are indicated in Figure 10, while the peak data are provided in Table 4.The peak data patterns were in accordance with those of zincian greenockite from the International Centre for Diffraction Data (ICDD) PDF No. 40-0835, suggesting the zinc greenockite of the Saishitang deposit is hexagonal.In comparison to No. 40-0835, the unit-cell data of the zinc greenockite of the Saishitang deposit had a smaller a parameter, but a larger c parameter and cell volume V.

Factors Influencing Composition of Zincian Greenockite
The experimental and natural assemblage data indicated that the zincian greenockite composition was influenced by the chemical composition of the ore fluid (e.g., the Zn/Cd ratio and possibly Cl − content [4]) and the physicochemical parameters (pH, f S 2 , f O 2 , aH 2 S) [4,7,42], of which temperature was most important.Fluid inclusion microthermometric data were obtained in previous studies [29,37,43]; however, the temperature of the sulfide-sulfosalt stage containing the zincian greenockite was not attained, due to the varying divisions of the different mineralization stages by different researchers [29,37,43]

Factors Influencing Composition of Zincian Greenockite
The experimental and natural assemblage data indicated that the zincian greenockite composition was influenced by the chemical composition of the ore fluid (e.g., the Zn/Cd ratio and possibly Cl − content [4]) and the physicochemical parameters (pH, fS2, fO2, aH2S) [4,7,42], of which temperature was most important.Fluid inclusion microthermometric data were obtained in previous studies [29,37,43]; however, the temperature of the sulfide-sulfosalt stage containing the zincian greenockite was not attained, due to the varying divisions of the different mineralization stages by different researchers [29,37,43].The temperature of Stages IV to VI was found to be 235-366 °C by He et al. (2013) [43], while in Lu et al. ( 2016) it was 205-360 °C [29].Zincian greenockite was thus formed between 205-360 °C.Furthermore, according the mineral assessment, it appeared later than the cobaltite, but earlier than native silver and native bismuth.The cobaltite contained 0.46-1.28wt % Fe, 31.90-33.81wt % Co, and 0.87-2.98wt % Ni, and plots in the area bellow 300 °C of the FeAsS-CoAsS-NiAsS figure (Figure 11) [44].The melting point of native bismuth is 271 °C.Therefore, the zincian greenockite was formed under temperatures between 300 and 271 °C.The EPMA data indicated that zincian greenockite contains 72.4-89.9mol % CdS, which was in accordance with the experimental data of the ZnS-CdS system at 250 °C [7], and furthermore, the composition and structure were in line with the greenockite series [45] (cited in [2]).The Zn content varied (5.61 to 21.7 mol % ZnS), similarl to other occurrences of greenockite in hydrothermal deposits [4,11], e.g., 6-11 mol % ZnS in the Madjarovo Pb-Zn deposit [21], the maximum difference The EPMA data indicated that zincian greenockite contains 72.4-89.9mol % CdS, which was in accordance with the experimental data of the ZnS-CdS system at 250 • C [7], and furthermore, the composition and structure were in line with the greenockite series [45] (cited in [2]).The Zn content varied (5.61 to 21.7 mol % ZnS), similarl to other occurrences of greenockite in hydrothermal deposits [4,11], e.g., 6-11 mol % ZnS in the Madjarovo Pb-Zn deposit [21], the maximum difference in different types of greenockite in the Caledonia Group being <1 to 25 mol % ZnS [11], and 42-59 mol % ZnS in the Tsumeb, southwest Africa [17].In comparison to other occurrences, the zincian greenockite in the Saishitang deposit could be divided into two phases (I and II).Even within each phase, the composition was inhomogeneous, e.g., Phase I contained 14.6-21.7 mol % ZnS and 72.4-82.2mol % CdS, while Phase II contained 5.6-9.1 mol % ZnS and 85.4-89.9mol % CdS.The differences between two phases of zincian greenockite may have been the result of variation of f S 2 , f O 2 , T, Zn/Cd ratio during formation.Minerals assembages and paragenentic sequences of the Stage VI that contained zincian greenockite were affected mainly by f S 2 ; thus, f S 2 was the key factor for the two phases.
Additionally, trace amounts of Cu and Sn can affect the chemical composition of greenockite, and the maximum Cu and Sn contents can reach 0.05 wt % [8,9].The Cu content of zincian greenockite of the Saishitang deposit varied from 0.06 to 2.39 wt %, which may also be a factor influencing its composition.

Zincian Greenockite Formed during the Skarn Mineraization Processes
Evidence from both this study and previous research [28,29] suggest that the Saishitang deposit experienced skarn and hydrothermal processes.During initial magmatic-hydrothermal processes, fluids were oxidized and magnetite was precipitated, and iron orebodies were formed locally.Following this, the fluid reduced and sulfides (e.g., pyrrhotite, pyrite cobaltite, bornite, and chalcopyrite) were formed, particularly bornite under low f S 2 fluids [3]; when the temperature decreased, sphalerite and galena were precipitated; and finally, during the sulfide-sulfosalt stage, oxidation of fluids occurred, and stromeyerite, zincian greenockite, and native silver and bismuth were formed.Thus the zincian greenockite was formed in a transforming environment from a reducing environment to an oxidizing one during the final stage of the mineralization process of the Saishitang Cu deposit.
The textural and mineral association of the zincian greenockite of the Saishitang deposit suggested that it is of hypogene origin.The greenockite may have been crystallized from low-Zn, high-Cd, late-stage hydrothermal fluids [11,21].

Conclusions
(1) The zincian greenockite of the Saishitang skarn deposit occurs in the chalcopyrite-bornite ores and was formed during the sulfide-sulfosalt stage of the mineralization process.The chemical composition shows that it contains two phases (I and II).Phase I contains high Zn (14.6 to 21.7 mol % ZnS) and low Cd (72.4 to 82.2 mol % CdS), while Phase II contains low Zn (5.6 to 9.1 mol % ZnS) and high Cd (85.4 to 89.9 mol % CdS).The XRD data indicate that the zincian is hexagonal.(2) Zincian greenockite was formed at temperatures of 300-270 • C in a reducing to oxidizing environment during the late mineralization stage of the Saishitang skarn Cu deposit.

Field
and textural relationships indicate that the skarn-and ore-forming processes can be divided into two periods and six stages, including: (1) the skarn period, which includes an anhydrous skarn stage (Stage I) and a hydrous skarn stage (Stage II); and (2) the hydrothermal period, including a magnetite stage (Stage III), a first sulfide stage (Stage IV), a second sulfide stage

Field
and textural relationships indicate that the skarn-and ore-forming processes can be divided into two periods and six stages, including: (1) the skarn period, which includes an anhydrous skarn stage (Stage I) and a hydrous skarn stage (Stage II); and (2) the hydrothermal period, including a magnetite stage (Stage III), a first sulfide stage (Stage IV), a second sulfide stage

Field 4 . 18 (
and textural relationships indicate that the skarn-and ore-forming processes can be divided into two periods and six stages, including: (1) the skarn period, which includes an anhydrous skarn stage (Stage I) and a hydrous skarn stage (Stage II); and (2) the hydrothermal period, including a magnetite stage (Stage III), a first sulfide stage (Stage IV), a second sulfide stage (Stage V), and a sulfide-sulfosalt stage (Stage VI).The paragenetic sequence of the Saishitang deposit is shown in Figure Minerals 2017, 7, 132 5 of Stage V), and a sulfide-sulfosalt stage (Stage VI).The paragenetic sequence of the Saishitang deposit is shown in Figure 4.

Figure 7 .
Figure 7. (a,b) Back-scattered electron images (BSE) of zincian greenockite; (c,e) X-ray element-distribution maps for Zn and Cd of zincian greenockite for the area shown in Figure 6d; (d,f) X-ray element-distribution maps for Zn and Cd of zincian greenockite for the area of Figure 6c.The two grains indicate that the distribution of Zn and Cd is inhomogeneous and demonstrate an inverse correlation between Zn and Cd in zincian greenockite.Two phases (I and II) are evident and discussed in the text.Mineral abbreviations: Zn-GR = zincian greenockite, Bn = bornite, Wtc = wittichenite, Gn = galena.

Figure 7 .
Figure 7. (a,b) Back-scattered electron images (BSE) of zincian greenockite; (c,e) X-ray elementdistribution maps for Zn and Cd of zincian greenockite for the area shown in Figure 6d; (d,f) X-ray element-distribution maps for Zn and Cd of zincian greenockite for the area of Figure 6c.The two grains indicate that the distribution of Zn and Cd is inhomogeneous and demonstrate an inverse correlation between Zn and Cd in zincian greenockite.Two phases (I and II) are evident and discussed in the text.Mineral abbreviations: Zn-GR = zincian greenockite, Bn = bornite, Wtc = wittichenite, Gn = galena.

Figure 9 .
Figure 9. Enlargement of Figure 7f showing the electron-probe microanalysis data of Cd and Zn in Phase I and Phase II of zincian greenockite.Spots 1, 2, 3, 5, & 7 are from Phase I (light yellow areas) and possess less than 67 wt % Cd, and spots 4, 6, & 8 are from Phase II (dark red areas) and possess more than 71 wt % Cd.

Figure 9 .
Figure 9. Enlargement of Figure 7f showing the electron-probe microanalysis data of Cd and Zn in Phase I and Phase II of zincian greenockite.Spots 1, 2, 3, 5, & 7 are from Phase I (light yellow areas) and possess less than 67 wt % Cd, and spots 4, 6, & 8 are from Phase II (dark red areas) and possess more than 71 wt % Cd.

Figure 9 .
Figure 9. Enlargement of Figure 7f showing the electron-probe microanalysis data of Cd and Zn in Phase I and Phase II of zincian greenockite.Spots 1, 2, 3, 5, & 7 are from Phase I (light yellow areas) and possess less than 67 wt % Cd, and spots 4, 6, & 8 are from Phase II (dark red areas) and possess more than 71 wt % Cd.

Figure 10 .
Figure 10.X-ray diffraction patterns of zincian greenockite from two analysis spots (a) spot 31ba3, and (b) spot 31ba2 (peak data listed in Table4) with the corresponding the International Centre for Diffraction Data references.

Figure 10 .
Figure 10.X-ray diffraction patterns of zincian greenockite from two analysis spots (a) spot 31ba3, and (b) spot 31ba2 (peak data listed in Table4) with the corresponding the International Centre for Diffraction Data references.

Table 1 .
EPMA data and atomic proportions of zincian greenockite.n/a: not analyzed; n/d: not detected; apfu: atoms per formula unit., wittichenite, tetrahedrite, stannoidite, and sphalerite were also analyzed by EPMA.The results are provided in Tables

Table 2 .
Representative EPMA data and atomic proportions of cobaltite.

Table 4 .
X-ray diffraction data for zinc greenockite in comparison with ICCD data.

Table 4 .
X-ray diffraction data for zinc greenockite in comparison with ICCD data.