Sunstone
Variety (Na,Ca)(Si,Al)4O8
Also called Heliolite and Aventurine feldspar
About it
Feldspar that glitters with tiny reflective plates of hematite, giving a golden to red spangle. Classic oligoclase sunstone comes from Norway and India; Oregon sunstone is a separate labradorite kind.
- Type
- Variety
- Group
- Oligoclase variety (plagioclase feldspar)
- Formula
- (Na,Ca)(Si,Al)4O8
- Hardness (Mohs)
- 6–6.5
- Specific gravity
- 2.62–2.67
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Triclinic
- Colours
- orange, red-brown, golden, with glittering spangles
- Transparency
- translucent, transparent
- Cleavage and fracture
- perfect in one direction, good in another; uneven fracture
Typical values: real specimens vary. For more, see mindat.org.