sedimentary

Jasper (likely yellow-brown jasper/chert)

Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides and other impurities

AI-generated identification · may be incorrect

Opaque mustard-brown to olive-brown, earthy to waxy luster, massive with no visible crystals or cleavage; Mohs hardness about 6.5–7, specific gravity approximately 2.6. The rounded, polished appearance suggests natural water wear or tumbling.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or replaces sediments, with iron oxides producing the brown-yellow coloration; commonly Precambrian to younger, depending on locality. This specimen may also be iron-rich chert or weathered jasper.

Uses & applications

Used as ornamental stone, beads, cabochons, carvings, lapidary material, and occasionally decorative aggregate; too small and irregular for construction use.

Geological facts

Jasper is a variety of opaque chalcedony and is defined more by appearance and texture than by a single chemical impurity. Its colors commonly reflect hematite, goethite, clay, or manganese minerals.

Field identification & locations

Identify it by its opaque appearance, glassy-to-waxy fracture, lack of cleavage, and ability to scratch ordinary glass; it should not fizz in dilute hydrochloric acid. Common in volcanic terrains, sedimentary iron formations, and river gravels worldwide.