Labradorite
Mineral (Ca,Na)(Si,Al)4O8
Also called Black moonstone
About it
Grey plagioclase that flashes blue, green, and gold as it turns (labradorescence); from Labrador, Finland (spectrolite), and Madagascar. Clear Oregon sunstone is labradorite with copper flakes.
- Type
- Mineral
- Group
- Silicate (tectosilicate), feldspar group
- Formula
- (Ca,Na)(Si,Al)4O8
- Hardness (Mohs)
- 6–6.5
- Specific gravity
- 2.68–2.72
- Streak
- white
- Lustre
- vitreous (glassy), pearly
- Crystal system
- Triclinic
- Colours
- grey, dark grey, black, colourless, yellow, with blue, green, and gold flashes
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- perfect and good in two directions at about 86°
Typical values: real specimens vary. For more, see mindat.org.