mineral

Tumbled jasper or chert

Microcrystalline quartz (SiO₂), likely jasper/chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque tan, ochre, cream, and reddish-brown mottling with a waxy to dull luster and no visible cleavage. The rounded shape and smooth surface indicate natural water wear or tumbling.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater replaced or cemented sediment, forming microcrystalline quartz in cavities or beds; the specimen’s exact geological age cannot be determined from the image. Jasper commonly forms in volcanic or sedimentary environments.

Uses & applications

Used as ornamental stone, cabochons, beads, carvings, and decorative tumbled material; generally not used structurally.

Geological facts

Jasper is an opaque variety of chalcedony, while chert is the broader rock term for dense microcrystalline quartz. Color commonly comes from iron oxides and other trace minerals.

Field identification & locations

Identify by its opaque, fine-grained appearance, glassy-to-waxy fracture, lack of cleavage, and ability to scratch ordinary glass. Common sources include the western United States, Mexico, Brazil, Madagascar, and Australia.