sedimentary

Jasper

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 on Mohs scale. Color: Green and reddish-brown (mottled). Luster: Dull to waxy. Crystal Structure: Hexagonal/Microcrystalline (Cryptocrystalline quartz). Cleavage: None (Conchoidal fracture). Specific Gravity: 2.58-2.91.

Hardness: 6
Color: Green and reddish-brown (mottled)
Luster: Dull to waxy

Identified June 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments. Over millions of years, the silica replaces the organic material or fills voids under pressure and heat. Found in metamorphic or sedimentary environments worldwide.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and decorative ornaments. Historically used for making tools due to its hardness and sharp cleavage edges.

Geological facts

Jasper is an opaque variety of chalcedony. The name 'Jasper' is derived from the Greek 'iaspis', meaning spotted stone. It has been used as a gemstone since antiquity and was mentioned in the Bible and ancient Greek texts.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife) and its smooth, waxy feel when wet. Often found in riverbeds or coastal areas as water-worn pebbles. Common in the Pacific Northwest, India, and Brazil.