Rock crystal
Variety SiO2
Also called Clear quartz and Quartz crystal
About it
Colourless, water-clear quartz, often in six-sided prisms with pointed ends. Classic sources include Arkansas, Brazil, Madagascar, and the Alps; it has been carved into crystal balls for centuries.
- 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
- colourless, water-clear
- Transparency
- transparent
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.