mineral

Weathered quartz-rich pebble, possibly milky quartz or chalcedony

Quartz, SiO₂; exact variety uncertain from the image

AI-generated identification · may be incorrect

White to translucent gray with tan-brown iron-oxide staining; vitreous to slightly waxy luster and irregular conchoidal fracture. Mohs hardness 7, no cleavage, trigonal crystal structure, and specific gravity about 2.65.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed in a silica-rich vein or cavity, then rounded and surface-weathered by stream or beach transport; the brown coloration reflects oxidized iron minerals. Its precise geological age cannot be determined visually.

Uses & applications

Common quartz is used in glass, ceramics, abrasives, electronics, and construction aggregate; attractive pieces are sold as inexpensive specimens or cabochon material.

Geological facts

Quartz is one of Earth’s most abundant minerals and is highly resistant to weathering, allowing it to survive as rounded pebbles. Iron staining can penetrate cracks and produce irregular yellow-brown patches.

Field identification & locations

Look for hardness sufficient to scratch ordinary glass, lack of cleavage, and a pale translucent interior; a steel knife should not scratch it. Common worldwide, especially in quartz veins, stream gravels, and eroded crystalline-rock terrains.