Millerite
NiSIMA symbol: Mlrgrandfathered
Millerite is a sulfide or sulfosalt mineral with the formula NiS, crystallizing in the trigonal system. It has a Mohs hardness of 3-3.5, typically gray or yellow in color, with a metallic luster, a specific gravity of 5.3-5.65. Its streak is black or green.
Photos
Crystallography
| Crystal system | trigonal crystal systemWikidata (CC0) |
|---|---|
| Space group | R 3 m :H |
| Cell (Å, °) | a = 9.619, b = 9.619, c = 3.1499; α = 90, β = 90, γ = 120 |
| Cell volume | 252.4 ų, Z = 9 |
| Axial ratios | 1.0000:1:0.3275calculated from COD 5000114 |
| Source structure | COD 5000114 (Canadian Mineralogist, 1974) — 1 of 4 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 1.863 | 2.777 | 2.512 | 4.809 | 2.227 | 2.946 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 85.7 | 54.2 | 52 | 46.6 | 45.9 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 5000114; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 5.374 g/cm³calculated from COD 5000114 |
|---|---|
| Hardness (Mohs) | 3-3.5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 5.3-5.65 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | gray, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | black, greensingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | metallicsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 90.76 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Ni 64.67%, S 35.33% |
Classification
| Nickel-Strunz (10th) | 2.CC.20Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 2.CC.20Wikidata (CC0) |