Mineralogical, chemical, and crystallographic properties of supergene jarosite-group minerals from the Xitieshan Pb-Zn sulfide deposit, northern Tibetan Plateau, China
| العنوان: | Mineralogical, chemical, and crystallographic properties of supergene jarosite-group minerals from the Xitieshan Pb-Zn sulfide deposit, northern Tibetan Plateau, China |
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| المؤلفون: | Lei Chen, Ming-Zhong He, William H. Benzel, Robert O. Rye, H.A. Lowers, Jian-Wei Li |
| المصدر: | Mineralogy and Petrology. 107:487-499 |
| بيانات النشر: | Springer Science and Business Media LLC, 2012. |
| سنة النشر: | 2012 |
| مصطلحات موضوعية: | chemistry.chemical_classification, Thermogravimetric analysis, Supergene (geology), Sulfide, Weathering, Electron microprobe, Hematite, engineering.material, Decomposition, Crystallography, Geophysics, chemistry, Geochemistry and Petrology, visual_art, Jarosite, visual_art.visual_art_medium, engineering, Geology |
| الوصف: | Supergene jarosite-group minerals are widespread in weathering profiles overlying Pb-Zn sulfide ores at Xitieshan, northern Tibetan Plateau, China. They consist predominantly of K-deficient natrojarosite, with lesser amounts of K-rich natrojarosite and plumbojarosite. Electron microprobe (EMP) analyses, scanning electron microcopy (SEM) investigation, and X-ray mapping reveal that the jarosite-group minerals are characterized by spectacular oscillatory zoning composed of alternating growth bands of K-deficient and K-bearing natrojarosite (K2O >1 wt.%). Plumbojarosite, whenever present, occurs as an overgrowth in the outermost bands, and its composition can be best represented by K0.29Na0.19Pb0.31Fe2.66Al0.22(SO4)1.65(PO4)0.31(AsO4)0.04(OH)7.37. The substitution of monovalent for divalent cations at the A site of plumbojarosite is charge balanced by the substitution of five-valent for six-valent anions in XO4 at the X site. Thermogravimetric analysis (TGA) of representative samples reveal mass losses of 11.46 wt.% at 446.6 °C and 21.42 wt.% at 683.4 °C due to dehydroxylation and desulfidation, respectively. TGA data also indicate that the natrojarosite structure collapses at 446.6 °C, resulting in the formation of NaFe(SO4)2 and minor hematite. The decomposition products of NaFe(SO4)2 are hematite and Na2SO4. Powder X-ray diffraction (XRD) analyses show that the jarosite-group minerals have mean unit-cell parameters of a = 7.315 A and c = 016.598 A. XRD and EMP data support the view that substitutions of Na for K in the A site and full Fe occupancy in the B site can considerably decrease the unit-cell parameter c, but only slightly increase a. The results from this study suggest that the observed oscillatory zoning of jarosite-group minerals at Xitieshan resulted mainly from substitutions of K for Na at the A site and P for S at the X site. |
| تدمد: | 1438-1168 0930-0708 |
| DOI: | 10.1007/s00710-012-0258-y |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_________::e14e07ffe2d544ee678b6150f97f9c16 https://doi.org/10.1007/s00710-012-0258-y |
| Rights: | CLOSED |
| رقم الانضمام: | edsair.doi...........e14e07ffe2d544ee678b6150f97f9c16 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 14381168 09300708 |
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| DOI: | 10.1007/s00710-012-0258-y |