Herkimer diamond
Variety SiO2
Also called Herkimer quartz
About it
Short, very bright, doubly terminated quartz crystals freed from pockets in dolostone around Herkimer County, New York. They are quartz, not diamond; many hold specks of black hydrocarbon.
- 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, sometimes with black specks
- Transparency
- transparent
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.