Dumortierite
Dumortierite is a vibrant blue borosilicate mineral found in high-temperature metamorphic and granitic pegmatite environments. Nevada's Lyon County has one of the largest dumortierite deposits in North America. When dumortierite grows as inclusions in quartz, it produces "dumortierite quartz" — a vivid blue massive quartz used extensively in lapidary work. The electric blue color rivals sodalite and lapis lazuli.
Physical Properties
Chemical Formula
Al₆.5–7BO₃(SiO₄)₃(O,OH)₃
Hardness (Mohs)
7–8.5
Color
Vivid blue, violet-blue, reddish-brown
Luster
Vitreous to silky
Crystal System
Orthorhombic
Streak
White
Cleavage
Good in one direction
Specific Gravity
3.26–3.41
🔍 Field Identification Tips
Vivid electric blue to violet-blue in silky fibrous or massive form. Hardness 7–8.5 (harder than most blue minerals). Vitreous to silky luster. Typically massive, not well-crystallized. Distinguished from sodalite by higher hardness and lack of white veining. Distinguished from azurite by hardness and non-metallic luster.
Varieties & Forms
📍 Where to Find Dumortierite in the US
Uses & Applications
Porcelain and ceramic manufacture (high alumina), cabochons and decorative stone, collectors specimens.
💰 Collector Value Guide
Rough: $5–$30/lb. Blue dumortierite quartz cabochons: $20–$150. Quality collector specimens: $30–$200.
Find Dumortierite With Our Tools
Use the We Lick Rocks app to identify specimens, find dig sites, and connect with local rockhounds.