sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, mustard yellow, or earthy tones; Luster: Vitreous to waxy; Crystal structure: Hexagonal (microcrystalline); Cleavage: None; Specific gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown, mustard yellow, or earthy tones
Luster: Vitreous to waxy

Identified April 17, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, mustard yellow, or earthy tones; Luster: Vitreous to waxy; Crystal structure: Hexagonal (microcrystalline); Cleavage: None; Specific gravity: 2.58-2.91

Formation & geological history

Usually forms in sedimentary environments when silica-rich fluids permeate through volcanic ash or other sediments. Over time, the silica crystallizes into a dense, opaque form of chalcedony.

Uses & applications

Commonly used for lapidary work, decorative cabochons, jewelry, beads, and as an ornamental gemstone. Historically used for making tools and seals.

Geological facts

The name comes from the Old French word 'jaspre,' meaning spotted or speckled stone. It was a favorite gemstone in the ancient world, mentioned in biblical texts and used in the breastplate of the High Priest.

Field identification & locations

Identify by its opacity (unlike translucent quartz), waxy luster, and conchoidal fracture. Often found as rounded pebbles in stream beds or along coastlines. It is globally abundant.