Polybasite
[Ag9CuS4][(Ag,Cu)6(Sb,As)2S7]IMA symbol: Plbredefined
Polybasite is a sulfide or sulfosalt mineral with the formula [Ag9CuS4][(Ag,Cu)6(Sb,As)2S7], crystallizing in the monoclinic system. It has a Mohs hardness of 2-3, typically black or red in color, with a metallic luster, a specific gravity of 6-6.2. Its streak is black.
Photos
Crystallography
| Crystal system | monoclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | C 1 2/c 1 |
| Cell (Å, °) | a = 26.2625, b = 15.1623, c = 24.1061; α = 90, β = 90.045, γ = 90 |
| Cell volume | 9599.04 ų, Z = 8 |
| Axial ratios | 1.7321:1:1.5899calculated from COD 9013299 |
| Source structure | COD 9013299 (American Mineralogist, 2009) — 1 of 4 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 3.013 | 3.168 | 2.883 | 1.895 | 2.543 | 3.167 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 51.3 | 40.2 | 31.7 | 28.5 | 26.1 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9013299; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 6.353 g/cm³calculated from COD 9013299 |
|---|---|
| Hardness (Mohs) | 2-3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 6-6.2 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | black, redsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | blacksingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | metallicsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Classification
| Nickel-Strunz (10th) | 2.GB.15Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 2.GB.15Wikidata (CC0) |
| Dana (8th) | 3.1.7.2Wikidata (CC0) |