Anhydrous calcium sulfate that converts to gypsum when exposed to water. Common in evaporite sequences. Color: White, bluish, violet, gray. Luster: Vitreous to pearly. Streak: White. Cleavage: Perfect in three directions at 90°. Hardness: 3-3.5. Transparency: Translucent to opaque. Crystal system: Orthorhombic. Chemical formula: CaSO₄. Specific gravity: 2.97. Formation: Forms from dehydration of gypsum at elevated temperatures or directly from highly saline waters. Common geological settings: Worldwide; found in evaporite deposits, salt domes, and hydrothermal veins. Common look-alikes and related entries: Gypsum, Calcite, Barite.
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
Editorial owner
GeoMiner
Last updated
2026-03-30T14:37:03.541419+00:00
Review status
Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Anhydrous calcium sulfate that converts to gypsum when exposed to water. Common in evaporite sequences.
How can you identify Anhydrite?
Compare several properties rather than relying on colour alone. This entry records colour: White, bluish, violet, gray; lustre: Vitreous to pearly; streak: White; Mohs hardness: 3-3.5; cleavage: Perfect in three directions at 90°; crystal system: Orthorhombic; transparency: Translucent to opaque. Confirm an important identification with additional field tests or qualified laboratory work.
How does Anhydrite form?
Forms from dehydration of gypsum at elevated temperatures or directly from highly saline waters.
Where is Anhydrite commonly found?
Worldwide; found in evaporite deposits, salt domes, and hydrothermal veins.
What is Anhydrite commonly confused with?
Anhydrite may be confused with Gypsum, Calcite, Barite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
JavaScript is loading the interactive GeoMiner experience. The identification tools provide educational candidates, not laboratory confirmation.
