metamorphic

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly quartz (SiO₂), possibly with feldspar, mica, and iron-oxide staining

AI-generated identification · may be incorrect

Typically Mohs hardness 7, gray to tan-brown, with a vitreous to dull weathered luster and granular interlocking quartz crystals; generally lacks strong cleavage and feels very hard and dense. The specimen shows rusty staining and possible mica or feldspar inclusions.

Identified August 31, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when quartz-rich sandstone was intensely metamorphosed, recrystallizing its grains into a tightly fused mass; age depends on the source formation and cannot be determined from the photograph. Common in metamorphic mountain belts and exposed stream gravels.

Uses & applications

Used as durable crushed stone, road aggregate, facing stone, and occasionally decorative material; attractive clean pieces may be collected, but this rough specimen has little commercial value.

Geological facts

Quartzite commonly breaks across grains rather than around them, unlike sandstone, and can scratch ordinary glass. Iron oxides produce the brown, gold, and reddish weathering colors visible here.

Field identification & locations

Look for a very hard, sugary or glassy texture, fused quartz grains, and resistance to scratching; a hand lens and glass-scratch test help distinguish it from sandstone. Common worldwide, especially in ancient shield and mountain regions.