sedimentary

Polished leopard-skin jasper

Jasper (microcrystalline quartz, SiO₂), commonly orbicular or brecciated varieties

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown, tan, gray, and black orbicular pattern with a waxy-to-glassy polish. It is cryptocrystalline quartz with no visible cleavage and typically high toughness; specific gravity is about 2.55–2.70.

Identified September 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids cement volcanic ash, breccia, or sediment, with iron and manganese producing the mottled colors; individual deposits range from Precambrian to younger volcanic-associated settings. The pictured piece is tumbled and polished.

Uses & applications

Used for cabochons, beads, carvings, bookends, and decorative objects; it has little industrial value compared with ordinary quartz.

Geological facts

Its “leopard spots” are orbicular or brecciated structures rather than animal markings. Jasper is a variety of opaque chalcedony/microcrystalline quartz.

Field identification & locations

Identify it by its opaque, non-fading earthy colors, very fine texture, lack of cleavage, and inability to scratch glass only variably depending on polish and composition. Common sources include Mexico, Madagascar, South Africa, and the western United States.