mineral
Herkimer Diamond (Quartz with Carbon Inclusions)
Silicon Dioxide (SiO2) with Anthraxolite inclusions
Hardness: 7.5 on Mohs scale; Color: Clear to smoky with black inclusions; Luster: Vitreous; Crystal structure: Hexagonal (doubly terminated); Cleavage: None; Specific Gravity: 2.65
- Hardness
- 7
- Color
- Clear to smoky with black inclusions
- Luster
- Vitreous
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Physical properties
Hardness: 7.5 on Mohs scale; Color: Clear to smoky with black inclusions; Luster: Vitreous; Crystal structure: Hexagonal (doubly terminated); Cleavage: None; Specific Gravity: 2.65
Formation & geological history
Formed in ancient shallow seas around 500 million years ago within the Little Falls Dolostone through precipitation from hydrothermal fluids. The black inclusions are typically anthraxolite (calcined coal or decayed organic matter).
Uses & applications
Highly prized by mineral collectors, used in wire-wrap jewelry, and used as 'metaphysical' healing crystals. Industrial quartz uses include electronics and glassmaking.
Geological facts
Despite the name, they are quartz crystals, not diamonds. They were first discovered by Mohawk Indians and early settlers in Herkimer County, New York. They are unique for being naturally doubly terminated (pointed at both ends).
Field identification & locations
Identified by their exceptional clarity and 18-faced crystal habit. Found by cracking open vugs (pockets) in dolostone outcrops. Most authentically sourced from Herkimer County, NY.
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