Picromerite
Picromerite (synonyms: schoenite, schönite) is a mineral from the class of hydrous sulfates lacking additional anions, and containing medium to large cations according to the Nickel–Strunz classification.
| Picromerite | |
|---|---|
Picromerite on halite | |
| General | |
| Category | Sulfate mineral |
| Formula (repeating unit) | K2Mg(SO4)2·6H2O |
| IMA symbol | Pmr |
| Strunz classification | 7.CC.60 |
| Dana classification | 29.03.06.01 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P21/a |
| Unit cell | a = 9.07, b = 12.21, c = 6.11 [Å]; β = 104,8°; Z = 2 |
| Identification | |
| Color | Colorless; white, grey, reddish, yellowish |
| Crystal habit | massive aggregates; crusts; prismatic crystals |
| Cleavage | perfect {201} |
| Mohs scale hardness | 2.5 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent |
| Density | 2.03 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.461 nβ = 1.463 nγ = 1.476 |
| Birefringence | δ = 0.015 |
| 2V angle | Measured: 47° |
| Solubility | in cold water |
| Taste | bitter |
| References | |
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