Calcite
Mineral CaCO3
Also called Dogtooth spar, Nailhead spar, and Calcspar
About it
Fizzes in cold dilute acid, is scratched by a knife, and breaks into perfect rhombs; clear pieces show double images. It takes more crystal forms than almost any mineral; Elmwood, Tennessee, and Iceland are classic sources.
- Type
- Mineral
- Group
- Carbonate, calcite group
- Formula
- CaCO3
- Hardness (Mohs)
- 3
- Specific gravity
- 2.71–2.72
- Streak
- white
- Lustre
- vitreous (glassy), pearly
- Crystal system
- Trigonal
- Colours
- colourless, white, yellow, orange, pink, green, blue, grey, brown
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect rhombohedral in three directions
- Under UV light
- often red, pink, orange, or blue under UV, varying by locality
Typical values: real specimens vary. For more, see mindat.org.