Erythrite
Co3(AsO4)2·8H2OIMA symbol: Erygrandfathered
Erythrite is a phosphate, arsenate, or vanadate mineral with the formula Co3(AsO4)2·8H2O, crystallizing in the monoclinic system. It has a Mohs hardness of 1.5-2.5, typically blue, gray, green or red in color, with an adamantine or dull luster, a specific gravity of 2.912. Its streak is blue.
Photos
Crystallography
| Crystal system | monoclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | C 1 2/m 1 |
| Cell (Å, °) | a = 10.251, b = 13.447, c = 4.764; α = 90, β = 104.98, γ = 90 |
| Cell volume | 634.4 ų, Z = 2 |
| Axial ratios | 0.7623:1:0.3543calculated from COD 5000227 |
| Source structure | COD 5000227 (European Journal of Mineralogy (1,1989-), 1996) — 1 of 2 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 6.723 | 3.23 | 7.974 | 2.744 | 3.006 | 2.715 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 39.1 | 36.2 | 27 | 27 | 21.8 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 5000227; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 3.122 g/cm³calculated from COD 5000227 |
|---|---|
| Hardness (Mohs) | 1.5-2.5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.912 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | blue, gray, green, redsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | bluesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | adamantine, dull, earthy, pearly, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 598.76 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Co 29.53%, As 25.03%, O 42.75%, H 2.69% |
Classification
| Nickel-Strunz (10th) | 8.CE.40Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 8.CE.40Wikidata (CC0) |
| Dana (8th) | 40.3.6.3Wikidata (CC0) |