metamorphic

Weathered quartz-rich rock, possibly quartzite

Quartzite (mostly microcrystalline SiO₂), tentative identification

AI-generated identification · may be incorrect

Tan-brown, opaque to slightly translucent, earthy/waxy luster with a massive granular texture and no obvious cleavage; estimated Mohs hardness 6.5–7 and specific gravity about 2.6. Iron-oxide staining and weathering likely produce the coloration.

Identified September 3, 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, commonly over hundreds of millions to billions of years. The specimen’s rounded edges indicate stream or surface weathering.

Uses & applications

Used as durable aggregate, road stone, landscaping material, and building stone; attractive pieces may be collected or polished, though this example appears low-grade for jewelry.

Geological facts

Quartzite is generally harder and more resistant to weathering than its sandstone precursor. A steel knife should not readily scratch a fresh surface, while quartz-rich grains may produce a glassy scratch on ordinary glass.

Field identification & locations

Common in metamorphic mountain belts worldwide, including the Appalachians, Rocky Mountains, Alps, and shield regions. Confirm by testing a fresh face for glass-scratching hardness and checking for fused quartz grains rather than sand-sized grains in a cement matrix.