metamorphic

Quartz-rich gray stone, likely quartzite

Quartzite; predominantly crystalline silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Hardness about 7 Mohs; gray, translucent at thin edges, with a glassy to dull luster and granular interlocking quartz texture. Cleavage is absent or very poor; fracture is irregular to conchoidal, and specific gravity is about 2.65.

Identified September 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when quartz-rich sandstone is subjected to heat and pressure, recrystallizing the grains; ages range from Precambrian to younger depending on the source terrain. The image may also represent a small rough quartz fragment, which cannot be distinguished confidently without tests.

Uses & applications

Quartzite is used as crushed stone, aggregate, flagstone, countertops, and decorative material; attractive pieces are collected. Common rough specimens typically have modest value.

Geological facts

Its interlocking quartz grains make it more resistant to weathering than the original sandstone. A steel knife should not scratch it, while quartz or a hardened steel point may scratch glass.

Field identification & locations

Common in metamorphic mountain belts worldwide, including the Appalachian Mountains, Alps, Himalayas, and western North America. Look for sugary granular texture and acid resistance; a glass-streak test and hardness test help confirm quartz content.