Chrysoprase
Quartz var. Chrysoprase (Chalcedony) · Semi-Precious Gemstone
Crystal System
Trigonal crystal system; Cryptocrystalline (microscopic aggregates) habit; often found in massive, botryoidal, or nodular forms.
Mineral Group
Silicates (Subgroup: Tectosilicates / Chalcedony species)
Chemical Formula
SiO2 (Silicon Dioxide) with Ni2+ (Nickel) inclusions
Formation Process
Hydrothermal or Sedimentary; it forms as a result of the deep weathering or lateritization of nickeliferous serpentinites or other ultramafic rocks.
About This Crystal
Appears as a vibrant apple-green to deep leek-green cryptocrystalline quartz. It is translucent to opaque with a waxy to vitreous luster. The specimen in the image shows a smooth, egg-shaped polish with internal veining and slight color zoning.
Physical Characteristics
Color: Apple green; Streak: White; Cleavage: None; Fracture: Conchoidal to splintery; Specific Gravity: 2.6–2.7; Fluorescence: Generally inert or weak green under UV light.
Optical Properties
Refractive Index: 1.530–1.544; Birefringence: Up to 0.004; Pleochroism: None (singly refractive aggregate); Optical phenomena: None usually, though high-quality stones show a glowing translucency.
Hardness & Durability
Origin Region
Queensland and Western Australia; Poland (Szklary); Brazil; Russia (Urals); and Arizona, USA. It forms in nickel-rich weathered serpentinite.
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Very good (due to microcrystalline structure); Stability: Stable but can dehydrate and fade if exposed to excessive heat or prolonged direct sunlight.
Care & Maintenance
Clean with warm, soapy water; avoid ultrasonic cleaners and steam cleaning which may cause thermal shock. Store in a cool, dark place to prevent the nickel inclusions from dehydrating and losing color saturation.
Rarity & Value
Uncommon; the most valuable variety of the chalcedony group. Value is determined by color saturation (vibrant green) and translucency. It is often imitation-treated using green-dyed agate.
Special Characteristics
The green color is derived from hydrated nickel silicates (like garnierite) rather than chromium or vanadium. It can show milky clouds or small dendritic inclusions.
Lore & History
Historically used by Ancient Greeks and Romans for seals and signets. In traditional lore, it is associated with the Heart Chakra and believed to promote optimism, joy, and emotional healing.