Gaylussite
Gaylussite is a carbonate mineral, a hydrated sodium calcium carbonate, formula Na2Ca(CO3)2·5H2O. It occurs as translucent, vitreous white to grey to yellow monoclinic prismatic crystals. It is an unstable mineral which dehydrates in dry air and decomposes in water.
| Gaylussite | |
|---|---|
| General | |
| Category | Carbonate mineral |
| Formula (repeating unit) | Na2Ca(CO3)2·5H2O |
| IMA symbol | Gyl |
| Strunz classification | 5.CB.35 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | I2/a |
| Identification | |
| Color | Colorless, white, yellow, and grey |
| Crystal habit | Tabular prismatic crystals also granular |
| Cleavage | perfect [110] |
| Fracture | Conchoidal, brittle |
| Mohs scale hardness | 2.5 |
| Luster | vitreous |
| Streak | white |
| Specific gravity | 1.93 – 1.99 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.444 nβ = 1.516 nγ = 1.523 |
| Birefringence | δ = 0.079 |
| Solubility | decomposes in water |
| Other characteristics | efflorescent |
| References | |
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