sedimentary

Yellow Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to brownish-yellow, Luster: Dull to vitreous, Crystal structure: Hexagonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific gravity: 2.58-2.91

Hardness: 6

Identified March 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from silica-rich groundwater that permeates through pore spaces in sedimentary or volcanic rock. It often originates from volcanic ash flows or hydrothermal activity of various geological ages, commonly found in deposits millions of years old.

Uses & applications

Predominantly used as a gemstone for jewelry (cabochons, beads), decorative ornaments, and in 'metaphysical' collections. Industrially, it has been used as a polishing abrasive in some historic contexts.

Geological facts

Jasper is an opaque variety of chalcedony. The yellow color is specifically caused by high concentrations of iron inclusions, particularly goethite. It has been used since ancient times by civilizations like the Egyptians for amulets.

Field identification & locations

Identify by its opacity (it does not transmit light even if thinly sliced), its smooth waxy or dull surface, and its resistance to scratching from steel. Commonly found in riverbeds and arid desert regions in the Western US, South Africa, and India.