Neptunite
KNa2LiFe2+2Ti2Si8O24IMA symbol: Nptgrandfathered
Neptunite is a silicate mineral with the formula KNa2LiFe2+2Ti2Si8O24, crystallizing in the monoclinic system. It has a Mohs hardness of 6.6, typically black or red in color, with a vitreous luster, a specific gravity of 8.284. Its streak is brown.
Photos
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Crystallography
| Crystal system | monoclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | C 1 c 1 |
| Cell (Å, °) | a = 16.427, b = 12.478, c = 9.975; α = 90, β = 115.56, γ = 90 |
| Cell volume | 1844.54 ų, Z = 4 |
| Axial ratios | 1.3165:1:0.7994calculated from COD 9005950 |
| Source structure | COD 9005950 (Physics and Chemistry of Minerals, 1991) — 1 of 5 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 9.545 | 3.51 | 2.933 | 3.181 | 2.832 | 2.162 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 65.6 | 61.3 | 53.5 | 47.7 | 41.7 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9005950; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 3.27 g/cm³calculated from COD 9005950 |
|---|---|
| Hardness (Mohs) | 6.6single sourceDana's System, 1st Appendix (1899) |
| Specific gravity | 8.284 g/cm3single sourceDana's System, 1st Appendix (1899) |
| Color | black, redsingle sourceDana's System, 1st Appendix (1899) |
| Streak | brownsingle sourceDana's System, 1st Appendix (1899) |
| Luster | vitreoussingle sourceDana's System, 1st Appendix (1899) |
Classification
| Nickel-Strunz (10th) | 9.EH.05Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.EH.05Wikidata (CC0) |
| Dana (8th) | 70.4.1.1Wikidata (CC0) |