igneous
Dumortierite Quartz
Dumortierite (Al7BO3(SiO4)3O3) within Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: Dark blue, violet-blue, Luster: Vitreous to dull, Crystal structure: Orthorhombic (dumortierite) within Trigonal (quartz), Cleavage: Distinct in one direction (dumortierite), none in quartz, Specific gravity: 2.65 - 3.4
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Physical properties
Hardness: 7 (Mohs scale), Color: Dark blue, violet-blue, Luster: Vitreous to dull, Crystal structure: Orthorhombic (dumortierite) within Trigonal (quartz), Cleavage: Distinct in one direction (dumortierite), none in quartz, Specific gravity: 2.65 - 3.4
Formation & geological history
Formed in high-temperature, aluminum-rich pegmatites and contact metamorphic rocks.
Uses & applications
Used primarily as an ornamental stone and occasionally in jewelry as a substitute for lapis lazuli.
Geological facts
Often called 'blue quartz', dumortierite quartz is actually massive quartz heavily included with dumortierite fibers, giving it a distinctive blue color.
Field identification & locations
Can be identified by its massive form, typical blue color, and quartz hardness. Often found in Brazil, Canada, France, Italy, Madagascar, Namibia, and the USA (Nevada).
