metamorphic

Blue quartzite or blue schist (likely quartzite)

Quartz-rich metamorphic rock; predominantly SiO₂, possibly with blue amphibole or dumortierite

AI-generated identification · may be incorrect

Hardness about 6.5–7; blue-gray, granular, with a dull to vitreous luster and no obvious cleavage. The rough, fractured texture and pale quartz-rich areas suggest quartzite, though image-only identification is uncertain.

Identified August 20, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone was metamorphosed under heat and pressure; blue coloration may come from riebeckite, glaucophane, or dumortierite. Such rocks commonly formed during Precambrian to Paleozoic mountain-building events.

Uses & applications

Used as decorative stone, lapidary material, aggregate, and occasionally countertops; attractive pieces may be cut or polished for cabochons and specimens.

Geological facts

Blue quartzite is commonly confused with sodalite, dumortierite quartz, or blue schist. A steel file should barely scratch it, while strong vinegar produces no reaction.

Field identification & locations

Look for fused quartz grains, hardness, and lack of carbonate fizz; blue schist typically shows platy foliation and blue amphibole. Similar material occurs in Brazil, Madagascar, Norway, the Alps, and western North America.