sedimentary

Jasper

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 Mohs; Color: Dark green with brown/tawny inclusions; Luster: Vitreous to waxy (when wet/polished); Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture)

Hardness: 6
Color: Dark green with brown/tawny inclusions
Luster: Vitreous to waxy (when wet/polished)

Identified July 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms through the deposition of silica from hydrothermal solutions or volcanic ash in sedimentary environments, often replacing organic materials or filling cavities. The green and brown hues indicate the presence of iron oxides and iron silicates.

Uses & applications

Primarily used as a gemstone for jewelry, cabochons, and decorative ornamental carvings. It is also a popular collector's stone due to its variety.

Geological facts

Jasper is an opaque variety of chalcedony. It has been used since ancient times for both its supposed magical properties and as a tool for making arrowheads due to its sharp conchoidal fracture.

Field identification & locations

Identify by its smooth texture, opacity (does not let light through even at edges), and hardness. Often found in riverbeds or coastal areas as rounded water-worn pebbles.