Anhydrite
Mineral CaSO4
Also called Angelite
About it
Like gypsum without the water: harder, denser, and breaking into blocky pieces along three cleavages at right angles. Forms thick beds in salt and evaporite deposits; pale blue nodules from Peru are sold as angelite.
- Type
- Mineral
- Group
- Sulfate, anhydrous
- Formula
- CaSO4
- Hardness (Mohs)
- 3–3.5
- Specific gravity
- 2.95–3
- Streak
- white
- Lustre
- vitreous (glassy), pearly, greasy
- Crystal system
- Orthorhombic
- Colours
- colourless, white, grey, pale blue, lavender, pink
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect and good in three directions at right angles, giving blocky pieces
Typical values: real specimens vary. For more, see mindat.org.