Green Chert
Silicon Dioxide var. Chert · Mineral Specimen / Common Decorative Stone
Crystal System
Trigonal/Microcrystalline; habit is typically massive, cryptocrystalline, or nodular
Mineral Group
Silicates (Tectosilicate subgroup / Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) with trace impurities of chlorite, epidote, or clay minerals
Formation Process
Sedimentary formation via chemical precipitation of silica-rich fluids or accumulation of siliceous microfossils (diatoms/radiolaria) in deep-sea environments
About This Crystal
An opaque to slightly translucent, olive-to-dull green stone with a waxy to sub-vitreous luster and a smooth, almost soapy feel on fresh surfaces
Physical Characteristics
Color: Olive green; Streak: White; Cleavage: None; Fracture: Prominent conchoidal (shell-like curves); Specific Gravity: 2.58–2.91; Fluorescence: Usually inert
Optical Properties
Refractive Index: 1.54–1.55; Birefringence: Extremely low (microcrystalline); Opacity: Opaque with translucent edges; No distinctive optical phenomena
Hardness & Durability
Origin Region
Globally distributed; notable green varieties found in California (Franciscan Complex), USA, and parts of Australia and India
Hardness & Durability
Mohs Hardness: 6.5 to 7; Toughness: Very high due to interlocking microcrystalline structure; Wearability: Excellent for all jewelry types
Care & Maintenance
Wash with warm soapy water; very resistant to chemicals and sunlight; stable for long-term storage and display
Rarity & Value
Common; value is generally low and based on size or aesthetic interest for lapidary work; treatments are rare but dyeing is possible
Special Characteristics
Displays sharp, curved edges when broken (conchoidal fracture), which historically made it ideal for stone tool production
Lore & History
Historically used by prehistoric cultures for knapping arrowheads and scrapers; in modern lore, green chert is associated with grounding, perseverance, and connection to the Earth's heart chakra.