Margarite
Mineral CaAl2(Al2Si2O10)(OH)2
Also called Pearl mica
About it
Pinkish to grey brittle mica, harder than muscovite with flakes that snap rather than spring back; often with corundum in emery, as at Chester, Massachusetts, and Naxos, Greece.
- Type
- Mineral
- Group
- Silicate (phyllosilicate), mica group
- Formula
- CaAl2(Al2Si2O10)(OH)2
- Hardness (Mohs)
- 3.5–4.5
- Specific gravity
- 2.99–3.08
- Streak
- white
- Lustre
- pearly, vitreous (glassy)
- Crystal system
- Monoclinic
- Colours
- grey, pale pink, yellow, green
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in one direction, brittle flakes
Typical values: real specimens vary. For more, see mindat.org.