metamorphic
Blue quartz-bearing rock, possibly dumortierite quartzite
Quartz (SiO₂) with blue dumortierite or riebeckite-group amphibole; identification is approximate from the photograph
AI-generated identification · may be incorrectHardness about 6.5–7; mottled blue-gray with white granular patches and a minor reddish inclusion. Typically has a vitreous-to-dull luster, massive granular texture, and no obvious cleavage; quartz is the dominant crystal structure.
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Physical properties
Hardness about 6.5–7; mottled blue-gray with white granular patches and a minor reddish inclusion. Typically has a vitreous-to-dull luster, massive granular texture, and no obvious cleavage; quartz is the dominant crystal structure.
Formation & geological history
Likely formed when silica-rich rock recrystallized during metamorphism, with blue accessory minerals producing the color. Precise age and locality cannot be determined visually.
Uses & applications
Used mainly as a lapidary, ornamental, or collector material when attractive; tougher pieces may be cut or polished for cabochons and decorative objects.
Geological facts
Blue quartz is uncommon compared with clear quartz, and its color may result from microscopic inclusions rather than the quartz itself. Similar-looking rocks include sodalite-bearing syenite, lazulite-bearing schist, and blue apatite aggregates.
Field identification & locations
Look for hard, glassy quartz grains that scratch ordinary glass, granular interlocking texture, and blue inclusions; a streak, hardness, and locality are needed for confirmation. Blue quartz occurrences are known from Brazil, Austria, Norway, and the United States.
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