Gem silica
Variety SiO2
Also called Chrysocolla chalcedony
About it
Chalcedony coloured vivid sky blue by chrysocolla, far harder and tougher than chrysocolla alone. The finest came from Arizona copper mines such as Inspiration and Ray; Peru also produces it.
- Type
- Variety
- Group
- Quartz variety (chalcedony)
- Formula
- SiO2
- Hardness (Mohs)
- 6.5–7
- Specific gravity
- 2.57–2.64
- Streak
- white
- Lustre
- waxy, vitreous (glassy)
- Crystal system
- Trigonal
- Colours
- bright blue, blue-green
- Transparency
- translucent
- Cleavage and fracture
- none; conchoidal to uneven fracture
Typical values: real specimens vary. For more, see mindat.org.