Anhydrite
Ca(SO4)IMA symbol: Anhgrandfathered
Anhydrite is a sulfate mineral with the formula Ca(SO4), crystallizing in the orthorhombic system. It has a Mohs hardness of 3-3.5, typically white, gray or red in color, with a greasy or pearly luster, a specific gravity of 2.899-2.985. Its streak is white or gray; cleavage is perfect.
Photos
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Crystallography
| Crystal system | orthorhombic crystal systemWikidata (CC0) |
|---|---|
| Space group | A m m a |
| Cell (Å, °) | a = 7.00032, b = 6.99234, c = 6.24097; α = 90, β = 90, γ = 90 |
| Cell volume | 305.487 ų, Z = 4 |
| Axial ratios | 1.0011:1:0.8925calculated from COD 9017809 |
| Source structure | COD 9017809 (Powder Diffraction, 2011) — 1 of 12 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 3.5 | 3.496 | 2.85 | 2.209 | 2.328 | 1.869 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 96.6 | 61.7 | 39 | 37 | 30.2 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9017809; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.96 g/cm³calculated from COD 9017809 |
|---|---|
| Hardness (Mohs) | 3.5single sourceWikidata (CC0) 3-3.5single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Specific gravity | 2.899-2.985 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892) |
| Color | gray, red, whitesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | whitesingle sourceWikidata (CC0) gray, whitesingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Luster | greasy, pearly, vitreousDana, System of Mineralogy, 6th ed. (1892) |
| Cleavage | perfectDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 136.14 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Ca 29.44%, S 23.55%, O 47.01% |
Classification
| Nickel-Strunz (10th) | 7.AD.30Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 7.AD.30Wikidata (CC0) |
| Dana (8th) | 28.3.2.1Wikidata (CC0) |