mineral

Polished/tumbled jasper or chert pebble

Microcrystalline quartz (SiO₂), likely ferruginous jasper/chert

AI-generated identification · may be incorrect

Opaque to slightly translucent brown, tan, gray, and reddish material with a waxy to glassy polish and no visible crystals; quartz hardness is about 7 Mohs, with conchoidal fracture and specific gravity near 2.6. Exact identification is limited because the surface is wet and polished.

Identified August 14, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, commonly with iron oxides producing red-brown coloration; ages vary widely from Precambrian to Cenozoic depending on locality. The specimen appears naturally rounded and subsequently polished or water-worn.

Uses & applications

Used as lapidary material for cabochons, carvings, beads, and decorative objects; jasper has modest jewelry and collector demand.

Geological facts

Jasper is an opaque variety of chalcedony or microcrystalline quartz, while chert is the broader silica-rich rock category. Red, yellow, and brown colors commonly reflect hematite or goethite inclusions.

Field identification & locations

Look for dense, fine-grained texture, lack of cleavage, waxy luster, and conchoidal fracture; a steel file should not easily scratch it, though surface coatings can mislead. Common sources include India, Madagascar, Brazil, Mexico, and many river gravels worldwide.