sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5 - 7 on the Mohs scale; Color: Reddish-brown due to iron inclusions with white quartz streaks; Luster: Vitreous to waxy; Crystal structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None, exhibits conchoidal fracture.

Hardness: 6
Luster: Vitreous to waxy

Identified April 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich fluids in volcanic cavities or sedimentary layers. The red color is typically caused by the oxidation of iron within the silica matrix during formation.

Uses & applications

Used primarily as a gemstone for jewelry, in lapidary work for cabochons and carvings, and as a decorative stone in collecting and spiritual practices.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. It was highly prized in the ancient world for its supposed healing properties and used in the breastplate of the high priest in biblical times.

Field identification & locations

Identify in the field by its opacity (it does not transmit light even at the edges), its hardness (can scratch glass), and its smooth, waxy feel when wet. Often found in gravel beds or near volcanic outcrops.