Whewellite
Mineral CaC2O4·H2O
About it
Colourless calcium oxalate crystals, often heart-shaped twins, found with coal and in concretions; the same compound makes up many kidney stones. Fine crystals come from coal mines in Saxony and the Czech Republic.
- Type
- Mineral
- Group
- Organic compound, oxalate
- Formula
- CaC2O4·H2O
- Hardness (Mohs)
- 2.5–3
- Specific gravity
- 2.21–2.23
- Streak
- white
- Lustre
- vitreous (glassy), pearly
- Crystal system
- Monoclinic
- Colours
- colourless, white, yellowish, brownish
- Transparency
- transparent, translucent
- Cleavage and fracture
- good in one direction; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.