sedimentary

Iron-rich chert or jasper

Microcrystalline quartz (SiO₂), commonly colored by hematite/goethite

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; rusty red-brown, black, and gray coloration; dull to waxy luster; very fine-grained with conchoidal fracture and no visible cleavage. The dark bands likely reflect iron-oxide-rich zones or organic/mineral impurities.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement fine sediment, often in ancient marine beds; iron oxidation produces the red coloration. Precise age cannot be determined from the photograph and may range from Precambrian to much younger.

Uses & applications

Used as decorative stone, lapidary material, cabochons, beads, and occasionally aggregate; attractive banded pieces are collected as jasper or chert.

Geological facts

Jasper is an opaque variety of chalcedony, while chert is the broader fine-grained silica-rock category; the boundary between them is often informal.

Field identification & locations

Identify by testing for glass-scratching hardness, opaque waxy appearance, and conchoidal edges; it commonly occurs in sedimentary formations, volcanic terrains, and iron-rich gravels worldwide. A definitive identification may require streak, density, and microscopic examination.