Stilpnomelane
(K,Ca,Na)(Fe,Mg,Al)8(Si,Al)12(O,OH)36·nH2OIMA symbol: Stpapproved
Stilpnomelane is a silicate mineral with the formula (K,Ca,Na)(Fe,Mg,Al)8(Si,Al)12(O,OH)36·nH2O. It has a Mohs hardness of 3-4, typically black, green or yellow in color, with a metallic or pearly luster, a specific gravity of 2.769.
Photos
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Crystallography
| Space group | P -1 |
|---|---|
| Cell (Å, °) | a = 22.2, b = 22.2, c = 17.835; α = 125.03, β = 95.98, γ = 120 |
| Cell volume | 5199.1 ų, Z = 24 |
| Axial ratios | 1.0000:1:0.8034calculated from COD 9010047 |
| Source structure | COD 9010047 (American Mineralogist, 1994) |
Powder X-ray diffraction (calculated)
| d (Å) | 12.181 | 4.06 | 2.59 | 2.599 | 2.594 | 3.045 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 7.6 | 5 | 5 | 5 | 3.3 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9010047; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.606 g/cm³calculated from COD 9010047 |
|---|---|
| Hardness (Mohs) | 3-4single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.769 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | black, green, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | metallic, pearly, submetallicsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Classification
| Nickel-Strunz (10th) | 9.EG.40Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.EG.40Wikidata (CC0) |