mineral

Tumbled quartz (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent white to gray, vitreous luster, trigonal crystal structure, and no cleavage (conchoidal fracture). The rounded shape indicates mechanical tumbling and polishing; yellow-brown areas may be iron staining or a surface coating.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallizes from silica-rich igneous, metamorphic, and hydrothermal fluids; individual crystals commonly formed over millions of years, while this specimen was recently tumbled. Common sources include Brazil, Madagascar, the United States, and worldwide quartz-bearing rocks.

Uses & applications

Used for ornaments, lapidary items, countertops, glass, electronics, and watches; attractive tumbled pieces are inexpensive collectible or decorative stones.

Geological facts

Quartz is one of Earth’s most abundant minerals and is piezoelectric, producing an electrical response under pressure.

Field identification & locations

Identify by its glassy appearance, lack of cleavage, hardness sufficient to scratch ordinary glass, and resistance to scratching by steel. Common tumbled specimens typically sell for $1–$10; larger, exceptionally clear pieces may reach $15–$30.