Rammelsbergite
NiAs2IMA symbol: Rmbgrandfathered
Rammelsbergite is a sulfide or sulfosalt mineral with the formula NiAs2, crystallizing in the orthorhombic system. It has a Mohs hardness of 5.5-6, typically white or red in color, with a metallic luster, a specific gravity of 6.9-7.2. Its streak is black or gray.
Photos
Crystallography
| Crystal system | orthorhombic crystal systemWikidata (CC0) |
|---|---|
| Space group | P n n m |
| Cell (Å, °) | a = 4.7583, b = 5.7954, c = 3.5449; α = 90, β = 90, γ = 90 |
| Cell volume | 97.755 ų, Z = 2 |
| Axial ratios | 0.8210:1:0.6117calculated from COD 9012572 |
| Source structure | COD 9012572 (Acta Chemica Scandinavica A, 1979) — 1 of 3 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 2.552 | 2.475 | 1.87 | 2.843 | 1.696 | 1.772 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 84.8 | 76.1 | 72 | 41.5 | 33.7 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9012572; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 7.085 g/cm³calculated from COD 9012572 |
|---|---|
| Hardness (Mohs) | 5.5-6single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 6.9-7.2 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | red, whitesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | black, graysingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | metallicsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 208.54 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Ni 28.15%, As 71.85% |
Classification
| Nickel-Strunz (10th) | 2.EB.15aWikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 2.EB.15aWikidata (CC0) |