mineral

Tumbled clear quartz (rock crystal)

Quartz — silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Colorless, transparent to translucent, with a glassy luster and no visible cleavage; hardness Mohs 7, trigonal crystal structure, and specific gravity about 2.65. The rounded shape indicates mechanical tumbling and polishing; surface inclusions or bubbles may be present.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallizes from silica-rich hydrothermal fluids, igneous melts, and sedimentary veins, spanning much of Earth’s geological history. This specimen has been human-shaped rather than naturally weathered.

Uses & applications

Used for jewelry, ornaments, metaphysical collections, abrasives, glass, electronics, and precision oscillators. Small common tumbled pieces have modest commercial value.

Geological facts

Quartz is one of the most abundant minerals in Earth’s continental crust and is piezoelectric. Clear quartz is often called rock crystal; visually similar glass is softer and may show bubbles or conchoidal fractures.

Field identification & locations

Check for hardness by testing glass (quartz should scratch it), a cool dense feel, and lack of bubbles; avoid damaging valuable pieces. Common sources include Brazil, Madagascar, the United States, and worldwide quartz veins.