mineral

Tumbled jasper or chert

Microcrystalline quartz (SiO₂), likely iron-stained jasper/chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, cream, and reddish mottling with a waxy to subvitreous luster, no visible crystal faces, and conchoidal fracture. The rounded shape indicates tumbling or natural abrasion.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or fills cavities in volcanic or sedimentary rocks, with iron oxides producing the brown-red colors. Most examples are geologically young relative to their host rocks, commonly Paleozoic–Cenozoic.

Uses & applications

Used for cabochons, beads, carvings, and inexpensive jewelry; larger jasper is also decorative stone. Common tumbled specimens generally have modest value.

Geological facts

Jasper is an opaque variety of chalcedony, whereas more translucent material is usually called agate or chalcedony. The image alone cannot reliably distinguish jasper from similarly colored chert or brecciated chalcedony.

Field identification & locations

Common worldwide, including India, Madagascar, Brazil, Mexico, the western United States, and Australia. Confirm with a hardness test against steel or glass, while avoiding damage to collectible pieces; it should not scratch quartz but can scratch glass.