mineral
Gypsum (Selenite sand)
Calcium sulfate dihydrate (CaSO4·2H2O)
Hardness: 2.0 (Mohs scale), Color: White to transparent, Luster: Pearly to earthy, Crystal structure: Monoclinic, Cleavage: Perfect, Specific gravity: 2.3
- Hardness
- 2
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Physical properties
Hardness: 2.0 (Mohs scale), Color: White to transparent, Luster: Pearly to earthy, Crystal structure: Monoclinic, Cleavage: Perfect, Specific gravity: 2.3
Formation & geological history
Evaporite mineral formed through the evaporation of mineral-rich water in playa lakes or basin environments, often during the Holocene epoch in specific desert regions.
Uses & applications
Used primarily in the production of plaster, drywall (gypsum board), soil conditioners in agriculture, and as a retarder in Portland cement.
Geological facts
The White Sands National Park in New Mexico contains the world's largest gypsum dune field, covering 275 square miles. Unlike quartz sand, gypsum sand does not absorb heat from the sun.
Field identification & locations
Identified by its white color, extreme softness (can be scratched with a fingernail), and lack of heat retention. Common in arid sedimentary basins and salt flats.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock