Gypsum
Ca(SO4)·2H2OIMA symbol: Gpgrandfathered
Gypsum is a sulfate mineral with the formula Ca(SO4)·2H2O, crystallizing in the monoclinic system. It has a Mohs hardness of 2, a calculated density of 2.31 g/cm3. Its streak is white.
Photos
.jpg){kind=link}
Crystallography
| Crystal system | monoclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | I 1 2/c 1 |
| Cell (Å, °) | a = 5.679, b = 15.202, c = 6.522; α = 90, β = 118.43, γ = 90 |
| Cell volume | 495.153 ų, Z = 4 |
| Axial ratios | 0.3736:1:0.4290calculated from COD 9017313 |
| Source structure | COD 9017313 (Acta Crystallographica, Section B, 1982) — 1 of 13 structures |
Powder X-ray diffraction (calculated)
| d (Å) | 4.281 | 7.601 | 3.064 | 2.874 | 2.683 | 2.087 |
|---|---|---|---|---|---|---|
| I/I₀ | 100 | 75.8 | 74 | 50.4 | 38.7 | 16.9 |
xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9017313; idealized occupancies, no preferred orientation.
Physical properties
| Density (calculated) | 2.31 g/cm³calculated from COD 9017313 |
|---|---|
| Hardness (Mohs) | 2single sourceWikidata (CC0) |
| Streak | whitesingle sourceWikidata (CC0) |
Chemistry (calculated)
| Molecular weight | 172.17 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Ca 23.28%, S 18.62%, O 55.76%, H 2.34% |
Classification
| Nickel-Strunz (10th) | 7.CD.40Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 7.CD.40Wikidata (CC0) |