| Mineral | GYPSUM |
| Chemistry | CaSO 4 ยท2H 2 O |
| Class | Sulfates |
| Uses | plaster, wall board, some cements, fertilizer, paint filler, ornamental stone, etc.. |
| Color | Colorless to white often tinged other hues due to impurities. |
| Luster | Sub-Vitreous |
| Transparency | crystals are transparent to translucent. |
| CrystalSystem | Monoclinic |
| CrystalHabits | include the tabular, bladed or blocky crystals with a slanted parallelogram outline.The pinacoid faces dominate with jutting prism faces on the edges of the tabular crystals.Long thin crystals show bends and some specimens bend into spirals called Ram s Horn Selenite Two types of twinning are common and one produces a spear head twin or swallowtail twin while the other type produces a fishtail twin . Also massive, crusty, granular, earthy and fiberous. |
| Cleavage | Perfect Perfect an easy on {010}almost micacaeous in some samples. |
| Fracture | good in one direction and distinct in two others.. |
| Hardness | 2 |
| SpecificGravity | 2.308 g/ccm |
| Streak | White. |
| AssociatedMinerals | Commonest of the sulphate mineralsgypsum is found in marine evaporitesin caves where the air is dry enough to allow it to be deposited and remainat fumarolesand in the oxidized zones of sulfide deposits on occasion. |
| Characteristics | thin crystals are flexible but not elastic, meaning they can be bent but will not bend back on their own.Also some samples are fluorescent.Gypsum has a very low thermal conductivity (hence it s use in drywall as an insulating filler). A crystal of Gypsum |
| Indicators | crystal habit, flexible crystals, cleavage and hardness. |
| DensityNote | light |
| IMAStatus | Approved |
| CellParameters | a = 5.678b = 15.2c = 6.52 β=118.43° |
| Ratio | a:b:c = 0.374 : 1 : 0.429 |
| OpticalType | Biaxial (+) |
| RI | n α =1.519 - 1.521 n β =1.522 - 1.523 n |
| Birefringence | δ=0.010 |
| SurfaceRelief | Low |
| Strunz | 6/C.22-20 6 : SulphatesChromatesMolybdates C : Water-bearing sulphates without unfamiliar anions. cations of medium size 22 : Bassanite - Ardealite series |
