Muscovite
Mineral KAl2(AlSi3O10)(OH)2
Also called Isinglass, Sericite, Mariposite, and White mica
Take care.
- Fragile: Handle it gently and pack it well; it breaks or crumbles easily.
About it
Silvery, flexible sheets that peel apart and spring back; books can be huge in pegmatites. Once used as window "isinglass"; green chrome-bearing muscovite is called fuchsite.
- Type
- Mineral
- Group
- Silicate (phyllosilicate), mica group
- Formula
- KAl2(AlSi3O10)(OH)2
- Hardness (Mohs)
- 2–2.5
- Specific gravity
- 2.77–2.88
- Streak
- white
- Lustre
- vitreous (glassy), pearly, silky
- Crystal system
- Monoclinic
- Colours
- colourless, silver, white, pale brown, green, pink, yellow
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect in one direction, flexible elastic sheets
Typical values: real specimens vary. For more, see mindat.org.