Chrysocolla
Chrysocolla is a hydrated copper silicate that forms the most vivid blue-green colors found in copper deposits. The standard material is too soft to cut, but when chrysocolla impregnates chalcedony it forms "gem silica" — one of the rarest and most valuable blue gemstones in the world, worth more per carat than many diamonds. Arizona's copper mining districts produce world-class specimens.
Physical Properties
Chemical Formula
Cu₂-xAlₓH₂-xSi₂O₅(OH)₄
Hardness (Mohs)
2.5–3.5
Color
Sky blue, blue-green, green, cyan
Luster
Vitreous to earthy
Crystal System
Amorphous (no crystal form)
Streak
White to light green
Cleavage
None
Specific Gravity
1.9–2.4
🔍 Field Identification Tips
Vivid blue-green to cyan color. Extremely soft (2.5–3.5 — fingernail can scratch it). Amorphous — no crystal form. Often coats rock surfaces. Distinguished from turquoise by lower hardness, different luster, and no matrix veining pattern. Gem silica variety is much harder (quartz reinforced).
Varieties & Forms
📍 Where to Find Chrysocolla in the US
Uses & Applications
Cabochons (especially gem silica — extremely valuable), decorative objects, collectors specimens.
💰 Collector Value Guide
Common material: $5–$30/lb. Quality specimens: $20–$200. Gem silica (chrysocolla-chalcedony): $50–$500/ct. Fine translucent blue gem silica: $500–$2,000/ct.
Find Chrysocolla With Our Tools
Use the We Lick Rocks app to identify specimens, find dig sites, and connect with local rockhounds.