Mineralpedia Details for Anhydrite
Anhydrite
Named from the Greek anydos, which means “waterless”, or “dry,” in reference to the lack of water in the composition as opposed to the very similar Gypsum, which contains water in its composition. Anhydrite is a common mineral that can be found in evaporate deposits, in cap rocks above salt domes, as a dehydration product of gypsum, in igneous rocks, fumarolic deposits, surrounding hydrothermal chimneys, and as an alteration product in hydrothermal mineral deposits. Associated minerals include gypsum, halite, sylvite, polyhalite, dolomite, calcite, magnesite, celestine, and sulfur. Anhydrite can be rehydrated to gypsum. Colorless to pale blue-violet, white, pink, brown, or gray tabular crystals that can occur in granular, nodular, divergent, fibrous masses. Anhydrite can have a pearly to vitreous to greasy luster.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/anhydrite.pdf
- Formula
- CaSO4
- Crystal System
- Orthorhombic
- Crystal Habit
- Massive - Granular, Massive - Fibrous, Plumose
- Cleavage
- Perfect, Perfect, Good
- Luster
- Vitreous - Pearly
- Color
- colorless, white, bluish white, violet white, dark gray
- Streak
- white
- Class
- Orthorhombic - Dipyramidal
- Fracture
- Brittle - Conchoidal
- Hardness
- 3.5
- WebMineral
- View Anhydrite
- Mindat
- View Anhydrite
Anhydrite from Homestake mine, Lawrence Co., South Dakota, United States
Colorless bladed to tabular anhydrite crystals from 8mm to 1 cm.
Anhydrite from Chihuahua, Mexico
Light blue long bladed Anhydrite crystal group.
Anhydrite from Strathcona mine, Sudbury, Ontario, Canada
Purple cleavages of Anydrite on matrix with some sulfides.
Anhydrite from Champion mine, Marquette Co., Michigan, United States
A good geological specimen from this important mine. It features crystalline light purple anhydrite throughout with Hematite(?).
