Cronstedtite
(Fe2+,Fe3+)3(Si,Fe3+)2O5(OH)4IMA symbol: Crograndfathered
Cronstedtite is a silicate mineral with the formula (Fe2+,Fe3+)3(Si,Fe3+)2O5(OH)4. It has a Mohs hardness of 3-5, typically black, brown, green or yellow in color, with a vitreous luster, a specific gravity of 3.34-3.35. Its streak is green.
Photos
Crystallography
| Space group | P 3 1 m |
|---|---|
| Cell (Å, °) | a = 5.494, b = 5.494, c = 7.09; α = 90, β = 90, γ = 120 |
| Cell volume | 185.334 ų, Z = 1 |
| Axial ratios | 1.0000:1:1.2905calculated from COD 9005752 |
| Source structure | COD 9005752 (European Journal of Mineralogy, 2006) — 1 of 5 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 2.561 | 7.09 | 3.545 | 2.171 | 1.792 | 1.586 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 82.4 | 46.3 | 39.6 | 35.8 | 25.1 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9005752; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 3.487 g/cm³calculated from COD 9005752 |
|---|---|
| Hardness (Mohs) | 3-5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 3.34-3.35 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | black, brown, green, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | greensingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Classification
| Nickel-Strunz (10th) | 9.ED.15Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.ED.15Wikidata (CC0) |
| Dana (8th) | 71.1.4.7Wikidata (CC0) |