sedimentary

Likely iron-rich chert or jasper

Microcrystalline quartz (SiO₂), variably stained by iron oxides/hydroxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown-red to gray, opaque, with waxy to dull luster and conchoidal fracture. The pale metallic-looking patches may be weathered iron mineralization or reflective fracture surfaces, not necessarily gold.

Identified August 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Most likely formed when silica-rich groundwater replaced or cemented sediment, with later iron staining; age cannot be determined from the photograph. Chert and jasper occur in sedimentary beds, nodules, and hydrothermal replacement zones.

Uses & applications

Used as aggregate, roadstone, ornamental stone, and lapidary material; attractive pieces may be cut or polished. Common specimens generally have modest commercial value.

Geological facts

Chert is composed of quartz crystals too small to see individually and commonly breaks with sharp, curved surfaces. A streak, hardness, density, and chemical test are needed to distinguish it from slag, quartzite, or metal-bearing ore.

Field identification & locations

Common in sedimentary terrains worldwide, including formations in North America, Europe, and Australia. It should scratch glass, resist a steel blade, and leave a white streak; gold would be malleable and leave a yellow metallic streak rather than fracture conchoidally.