metamorphic

Blue-gray quartz-rich rock, possibly quartzite

Quartzite (mostly SiO₂), possibly with mica or feldspar

AI-generated identification · may be incorrect

Hardness about 7 Mohs; pale blue-gray, granular and unevenly translucent, with a vitreous to dull luster. The specimen appears massive and lacks obvious cleavage, consistent with interlocking quartz grains.

Identified September 7, 2026More metamorphic →

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Physical properties

Formation & geological history

Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism. Its age depends on the source formation; similar rocks occur in Precambrian through younger metamorphic terrains.

Uses & applications

Used as crushed stone, construction aggregate, paving, and durable building stone; attractive pieces may be collected or polished, though this small specimen has limited gem value.

Geological facts

Blue-gray coloration can result from inclusions of mica, amphibole, or other minerals rather than quartz itself. A scratch test on glass can help distinguish quartzite from softer look-alikes.

Field identification & locations

Common in metamorphic mountain belts and resistant ridges worldwide. Confirm by testing whether it scratches glass, examining interlocking grains with a loupe, and checking for weak acid reaction; exact identification requires hardness and petrographic testing.