Herkimer Diamond (Quartz)
Quartz var. Herkimer Diamond · Semi-Precious Gemstone / Mineral Specimen.
Crystal System
Trigonal system; typically occurs as doubly terminated hexagonal prisms with 18 total facets.
Mineral Group
Silicates; Tectosilicate subgroup.
Chemical Formula
SiO2 (Silicon Dioxide)
Formation Process
Sedimentary-hydrothermal; formed very slowly in pockets of dolostone from silica-rich solutions at relatively low temperatures.
About This Crystal
Double-terminated, water-clear to smoky crystal. High vitreous luster with exceptional transparency. Frequently contains 'anthraxolite' (black carbon) inclusions or skeletal growth patterns.
Physical Characteristics
Colorless to smoky; white streak; no cleavage; conchoidal fracture; specific gravity 2.65; often displays yellow/blue fluorescence if petroleum inclusions are present.
Optical Properties
Refractive index 1.544–1.553; double refraction (+0.009); uniaxial; vitreous luster; no pleochroism.
Hardness & Durability
Origin Region
The Mohawk River Valley and Herkimer County, New York, USA. Found in Little Falls dolostone cavites (vugs).
Hardness & Durability
7 on the Mohs scale; extremely durable and stable for all jewelry types; resistant to most household chemicals.
Care & Maintenance
Clean with warm soapy water; safe for ultrasonic cleaners; avoid extreme thermal shock; store separately to prevent scratching softer stones.
Rarity & Value
Common globally as Quartz, but genuine Herkimer-sourced specimens are locally specific and highly valued for their natural geometry. Price varies by clarity and size.
Special Characteristics
Double termination (points at both ends); frequent black hydrocarbon inclusions; occasional enhydro (liquid) or bridge crystal formations.
Lore & History
Historically used by the Mohawk people and early settlers as amulets. Spiritually known as 'stones of attunement' associated with the Crown Chakra and high-frequency energy.