Rock Identifier
Polished white quartz-rich pebble (Microcrystalline quartz (SiO₂), likely milky quartz or quartzite) — mineral
mineral

Polished white quartz-rich pebble

Microcrystalline quartz (SiO₂), likely milky quartz or quartzite

AI-generated identification · may be incorrect

Hardness about 7 Mohs; white to gray, waxy-to-glassy luster, massive granular texture, no obvious cleavage, and typical specific gravity near 2.65. The dark gray patches may be mineral inclusions or surface staining.

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Physical properties

Hardness about 7 Mohs; white to gray, waxy-to-glassy luster, massive granular texture, no obvious cleavage, and typical specific gravity near 2.65. The dark gray patches may be mineral inclusions or surface staining.

Formation & geological history

Likely a naturally rounded stream or glacial pebble composed of quartz/quartzite; quartz formed in silica-rich veins or metamorphic rocks, commonly Precambrian to younger. Subsequent erosion produced its smooth shape.

Uses & applications

Used mainly as a decorative, lapidary, or collection stone; quartz-rich pebbles can also serve as aggregate, but this small specimen has little industrial value.

Geological facts

Quartz is one of Earth’s most abundant minerals and is harder than ordinary steel, though it can still fracture conchoidally. Its cloudy appearance results from microscopic fluid inclusions, fractures, or intergrown crystals.

Field identification & locations

Scratch-testing with a steel knife should not mark it, while a quartz crystal should scratch it; inspect for granular quartz texture and absence of fizz in dilute acid. Common in stream gravels and glacial deposits worldwide.