mineral

Tumbled quartz or chalcedony (uncertain)

Quartz, SiO₂; possibly cryptocrystalline chalcedony

AI-generated identification · may be incorrect

Small rounded, polished specimen with a creamy tan color and apparently translucent edges. Likely Mohs hardness 6.5–7, glassy to waxy luster, no obvious cleavage, and specific gravity about 2.6; the image is too blurred for confident texture or crystal identification.

Identified August 21, 2026More mineral →

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Physical properties

Formation & geological history

Quartz/chalcedony forms in silica-rich veins, cavities, and volcanic rocks, commonly through hydrothermal deposition or later silicification. Tumbled pieces are human-polished and have no meaningful specimen-specific age.

Uses & applications

Used as an ornamental stone, lapidary material, aggregate, and in glass and electronics; attractive translucent pieces may be used in jewelry. Common tumbled material is generally low value.

Geological facts

The rounded shape and smooth surface strongly suggest tumbling rather than natural weathering. Tan coloration may result from iron staining or inclusions.

Field identification & locations

A hardness test, streak test, and stronger light from behind would help: quartz does not scratch with a steel knife easily and leaves a white streak. Quartz and chalcedony are common in northern California, including the broader region near 40.2°N, 123.6°W.