metamorphic
Blue-gray quartz-bearing rock, likely dumortierite quartz or silicified metamorphic rock
Quartz (SiO₂) with probable dumortierite and iron-oxide inclusions
AI-generated identification · may be incorrectHardness about 7 (quartz); blue-gray, black, white, and rusty-orange patches; vitreous to sugary luster; massive, granular texture with no obvious cleavage. The color and translucent zones suggest quartz-rich material rather than a single pure mineral.
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Physical properties
Hardness about 7 (quartz); blue-gray, black, white, and rusty-orange patches; vitreous to sugary luster; massive, granular texture with no obvious cleavage. The color and translucent zones suggest quartz-rich material rather than a single pure mineral.
Formation & geological history
Likely formed when silica-rich fluids altered or recrystallized an older rock during metamorphism; the specimen has no reliable age information from the image. Iron oxides probably produced the orange-brown staining.
Uses & applications
Potentially usable as a lapidary or decorative stone if it takes a good polish, though the visible fractures may limit quality; not normally an industrial-grade ore.
Geological facts
Dumortierite-bearing quartz commonly ranges from pale to deep blue and is sometimes marketed as “blue quartz.” Similar appearance can also result from blue chalcedony, sodalite-bearing rock, or altered granite.
Field identification & locations
Look for quartz’s glassy fracture, resistance to scratching, and granular intergrowth; a steel file should not scratch fresh quartz. Exact identification requires hardness, streak, translucency, and ideally microscopy or chemical testing; common sources include Brazil, Madagascar, the United States, and Europe.
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