Bytownite
Mineral (Ca,Na)(Si,Al)4O8
About it
Calcium-rich plagioclase (70 to 90 per cent anorthite), named for Bytown, the old name of Ottawa. Pale yellow gem crystals are cut from volcanic rock in Mexico.
- Type
- Mineral
- Group
- Silicate (tectosilicate), feldspar group
- Formula
- (Ca,Na)(Si,Al)4O8
- Hardness (Mohs)
- 6–6.5
- Specific gravity
- 2.72–2.74
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Triclinic
- Colours
- white, grey, pale yellow, colourless
- Transparency
- transparent, translucent
- Cleavage and fracture
- perfect and good in two directions at about 86°
Typical values: real specimens vary. For more, see mindat.org.