Crocoite
Pb(CrO4)IMA symbol: Crcgrandfathered
Crocoite is a sulfate mineral with the formula Pb(CrO4), crystallizing in the monoclinic system. It has a Mohs hardness of 2.5-3, typically red in color, with an adamantine or vitreous luster, a specific gravity of 5. Its streak is orange or yellow.
Photos
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Crystallography
| Crystal system | monoclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | P 1 21/n 1 |
| Cell (Å, °) | a = 7.098, b = 7.41, c = 6.779; α = 90, β = 102.4, γ = 90 |
| Cell volume | 348.232 ų, Z = 4 |
| Axial ratios | 0.9579:1:0.9148calculated from COD 9017805 |
| Source structure | COD 9017805 (Physical Review, 2012) — 1 of 4 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 3.268 | 3.023 | 3.466 | 4.365 | 2.085 | 4.937 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 61.2 | 58.5 | 32.7 | 29.4 | 25.9 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9017805; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 6.156 g/cm³calculated from COD 9017805 |
|---|---|
| Hardness (Mohs) | 2.5-3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 5 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | redsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | orange, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | adamantine, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 323.19 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Pb 64.11%, Cr 16.09%, O 19.8% |
Classification
| Nickel-Strunz (10th) | 7.FA.20Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 7.FA.20Wikidata (CC0) |