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Kenorozhdestvenskayaite-(Fe), Ag6(Ag4Fe2)Sb4S12□: A new tetrahedrite group mineral containing a natural [Ag6]4+ cluster and its relationship to the synthetic ternary phosphide (Ag6M4P12)M 6 ′
- Source :
- American Mineralogist; Jul2024, Vol. 109 Issue 7, p1275-1283, 9p
- Publication Year :
- 2024
-
Abstract
- [Ag<subscript>6</subscript>]<superscript>4+</superscript> clusters are extremely rare in nature (only found in Ag-rich tetrahedrite group minerals). Due to their remarkable structures and some promising applications, a few synthesis phases that contain octahedral [Ag<subscript>6</subscript>]<superscript>4+</superscript> clusters have been reported. However, the kinds of natural conditions that promote the formation of subvalent hexasilver clusters in tetrahedrite group minerals are still unclear. Kenorozhdestvenskayaite-(Fe), ideally Ag<subscript>6</subscript>(Ag<subscript>4</subscript>Fe<subscript>2</subscript>)Sb<subscript>4</subscript>S<subscript>12</subscript>□ is a new tetrahedrite group mineral containing a natural [Ag<subscript>6</subscript>]<superscript>4+</superscript> cluster, found in the Yindongpo gold deposit, Weishancheng ore field, Henan Province, China. This new species occurs at the edges of galena crystals as anhedral grains of 2 to 20 μm in size and is associated with pyrargyrite, pyrrhotite, and siderite. Kenorozhdestvenskayaite-(Fe) is black in color with metallic luster. It is brittle with conchoidal fracture and has a calculated density of 5.329 g/cm<superscript>3</superscript>. The empirical formula calculated on the basis of cation = 16 apfu is <superscript>M(2)</superscript>Ag<subscript>6</subscript><superscript>M(1)</superscript>(Ag<subscript>2.41</subscript>Cu<subscript>1.20</subscript>Fe<subscript>1.84</subscript>Zn<subscript>0.71</subscript>)<subscript>Σ6.16</subscript><superscript>X(3)</superscript>(Sb<subscript>3.82</subscript>As<subscript>0.01</subscript>)<subscript>Σ3.83</subscript><superscript>S(1)</superscript>S<subscript>11.60</subscript><superscript>S(2)</superscript>□. It is cubic, with space group I 4 3m, a = 10.7119(6) Å, V = 1229.1(2) Å<superscript>3</superscript>, and Z = 2. Since kenorozhdestvenskayaite-(Fe) is a new tetrahedrite group mineral containing a natural [Ag<subscript>6</subscript>]<superscript>4+</superscript> cluster, its structure is comparable to the synthetic ternary phosphide (Ag<subscript>6</subscript>M<subscript>4</subscript>P<subscript>12</subscript>) M 6 ′ . The presence of the unusual mineral assemblages, i.e., pyrrhotite and pyrargyrite, as well as the other keno-end-member tetrahedrites, indicates a low-f<subscript>S<subscript>2</subscript></subscript> state for the mineralization stage, probably a result of the fluid boiling process in an open system that likely contributed to the formation of S-deficient tetrahedrites. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0003004X
- Volume :
- 109
- Issue :
- 7
- Database :
- Complementary Index
- Journal :
- American Mineralogist
- Publication Type :
- Academic Journal
- Accession number :
- 178334114
- Full Text :
- https://doi.org/10.2138/am-2023-9074