sedimentary

Banded chert or jasper (likely iron-rich jasper)

Microcrystalline quartz (SiO₂), commonly with hematite/goethite and clay impurities

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque olive-brown to reddish-brown with dark bands, earthy-to-waxy luster, and no visible cleavage. It is dense, fine-grained cryptocrystalline quartz and appears naturally weathered or roughly polished.

Identified September 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediments, often incorporating iron oxides that create red, brown, and dark bands; ages range from Precambrian to younger sedimentary deposits. Common in iron formations, volcanic-sedimentary terrains, and river gravels.

Uses & applications

Used as an ornamental stone, lapidary rough, cabochons, beads, and limited aggregate or decorative tile. Value is mainly aesthetic and usually modest.

Geological facts

Jasper is a variety of opaque chalcedony/chert; its colors commonly reflect hematite (red) and goethite or other iron minerals (brown-yellow).

Field identification & locations

Identify by its glassy or waxy fracture, extreme toughness, fine texture, and inability to scratch with a steel knife; it should not fizz in dilute acid. Common sources include India, Madagascar, Australia, Brazil, and the western United States.