Herkimer Diamond
Quartz var. Herkimer Diamond · Collector Mineral / Semi-Precious Gemstone
Crystal System
Trigonal; typically exhibits a doubly terminated (six-sided) prismatic habit with steep rhombohedrons.
Mineral Group
Silicates (Tectosilicate subgroup)
Chemical Formula
SiO2 (Silicon Dioxide) with common hydrocarbon inclusions
Formation Process
Hydrothermal; formed in vugs (cavities) within sedimentary dolostone roughly 500 million years ago at low temperature.
About This Crystal
Short, stubby, doubly terminated crystals that are exceptionally transparent with a high vitreous luster. Often contains black carbonaceous or hydrocarbon inclusions.
Physical Characteristics
Colorless/Transparent; White streak; No cleavage; Conchoidal fracture; Specific gravity 2.65; Fluoresces yellow or orange under longwave UV if petroleum inclusions are present.
Optical Properties
Refractive index: 1.544–1.553; Double refraction (uniaxial positive); Low dispersion; No pleochroism.
Hardness & Durability
Origin Region
Herkimer County, New York, USA; found in Little Falls Dolostone.
Hardness & Durability
Mohs hardness 7.0; High durability and stability; good for all jewelry types despite being brittle.
Care & Maintenance
Clean with warm soapy water; safe for ultrasonic cleaners unless large inclusions are liquid-filled; store away from harder stones like Sapphire or Diamond.
Rarity & Value
Uncommon; value depends on clarity and the perfection of terminations; size is a major price factor as large clear specimens are rare.
Special Characteristics
Natural double termination; often contains 'anthraxolite' (black carbon) or 'enhydro' (moving water bubbles) inclusions.
Lore & History
Historically used by the Mohawk people; traditionally known as the 'Stone of Attunement' in crystal healing, believed to amplify energy and mental clarity.