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 incorrectHardness 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 More metamorphic →
Explore Blue quartzite or blue schist (likely quartzite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
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.
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.
More like this
