mineral

Tumbled quartz pebble

Quartz (silicon dioxide, SiO₂), likely milky or smoky quartz

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent gray-white color, vitreous-to-waxy luster, and no visible cleavage. Quartz is trigonal and has a specific gravity of about 2.65; the rounded shape indicates natural abrasion or tumbling.

Identified September 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich igneous, metamorphic, or hydrothermal rocks, commonly millions to billions of years old. This small specimen was likely worn in sediment or artificially tumbled and polished.

Uses & applications

Used in glass, ceramics, electronics, abrasives, countertops, and gemstone cabochons; this example is mainly a low-grade decorative or educational specimen.

Geological facts

Quartz is one of Earth’s most abundant minerals and is chemically resistant, allowing it to survive transport as a rounded pebble. The image does not show diagnostic crystal faces or inclusions sufficient for a more specific variety.

Field identification & locations

Identify it by its glassy appearance, lack of cleavage, hardness—scratching ordinary glass—and conchoidal fracture. Common in stream gravels and quartz veins worldwide, especially Brazil, Madagascar, India, and the United States.