Smoky quartz
Variety SiO2
Also called Cairngorm
Take care.
- Sensitive to heat: Keep it away from heat and sudden changes of temperature, including hot lights and ultrasonic cleaners.
About it
Brown to grey quartz darkened by natural radiation acting on traces of aluminum; heat bleaches it. Fine crystals come from the Swiss Alps, the Pikes Peak area of Colorado, and the Cairngorms of Scotland.
- Type
- Variety
- Group
- Quartz variety
- Formula
- SiO2
- Hardness (Mohs)
- 7
- Specific gravity
- 2.65–2.66
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Trigonal
- Colours
- light brown, smoky grey, dark brown, nearly black
- Transparency
- transparent, translucent
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.