sedimentary

Tumbled brown stone, likely chert or jasper

Microcrystalline quartz (SiO₂), possibly iron-stained chert/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown to gray-brown with a smooth tumbled surface, dull to waxy luster, and no visible cleavage. Its compact, fine-grained texture is consistent with chalcedony or chert.

Identified September 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert and jasper form when silica-rich fluids replace or cement sediments, commonly in marine or volcanic-associated environments; specimens may range from Precambrian to younger sedimentary ages. The rounded shape indicates human tumbling or natural abrasion.

Uses & applications

Used as a low-cost lapidary material for cabochons, beads, carvings, and decorative stones; historically, chert was important for tools and fire-starting. Common pieces have modest collector value.

Geological facts

The image does not show diagnostic banding or distinct crystals, so exact identification is uncertain from appearance alone. A steel file or glass scratch test can help distinguish quartz-rich material from softer rocks.

Field identification & locations

Common in sedimentary formations and gravel deposits worldwide, especially where silica-rich rocks weather. Look for conchoidal fracture, very high hardness, and a waxy surface; acid typically produces no reaction.