sedimentary

Tumbled brown chert or jasper

Microcrystalline quartz (SiO₂), likely chalcedony/chert with iron-oxide impurities

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown to olive-brown, waxy to dull luster, cryptocrystalline quartz, with no visible cleavage. The rounded, glossy surface indicates tumbling or water abrasion.

Identified September 22, 2026More sedimentary →

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Physical properties

Hardness about 6.5–7 Mohs; opaque brown to olive-brown, waxy to dull luster, cryptocrystalline quartz, with no visible cleavage. The rounded, glossy surface indicates tumbling or water abrasion.

Formation & geological history

Forms when silica-rich groundwater replaces or fills pores in sedimentary rocks; iron oxides create the brown coloration. Chert and jasper range from Precambrian to recent ages and occur in many sedimentary environments.

Uses & applications

Used as an ornamental stone, lapidary material, worry stone, and occasionally in low-cost jewelry or carvings; not generally used structurally.

Geological facts

Chert is typically relatively uniform and waxy, while jasper is more opaque and iron-rich with stronger coloration or patterns. A steel file should not easily scratch it, and it may produce a glassy edge when fractured.

Field identification & locations

Common in river gravels, limestone beds, volcanic terrains, and commercial tumbled-stone assortments worldwide. Identification is best confirmed by hardness, conchoidal fracture, and absence of visible grains or cleavage.