sedimentary

Jasper

Silicon dioxide (SiO2) with impurities

Hardness: 6.5-7 (Mohs scale); Color: Yellow and Dark Grey/Black (pictured); Luster: Vitreous to greasy; Crystal Structure: Microcrystalline (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Yellow and Dark Grey/Black (pictured)
Luster: Vitreous to greasy

Identified March 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from water solutions into fissures or volcanic ash. The process involves high heat and pressure, often occurring near volcanic activity or in sedimentary environments over millions of years (Paleozoic to Cenozoic eras).

Uses & applications

Used primarily in lapidary arts for jewelry, beads, and cabochons. Historically used for architectural inlay, ornamental boxes, and seals. Also used in modern construction as decorative aggregate.

Geological facts

Jasper is an opaque variety of chalcedony. The name 'Jasper' is derived from the Greek word 'iaspis', meaning spotted stone. It has been used since antiquity; the Bible mentions it as one of the stones in the breastplate of the high priest.

Field identification & locations

Identify by its opacity (it does not transmit light even on thin edges), its hardness (it will scratch glass), and its smooth, waxy feel. Commonly found in riverbeds and arid regions globally, notably in the USA (Oregon, Idaho), India, and Brazil.