sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7.0 (Mohs scale); Color: Red, purple, brownish-red due to iron inclusions; Luster: Dull to vitreous; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Red, purple, brownish-red due to iron inclusions
Luster: Dull to vitreous

Identified April 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of fine silica-rich sediment or volcanic ash, occurring in hydrothermally altered environments or as nodules in sedimentary rocks. Often dates back to various geological eras including the Proterozoic.

Uses & applications

Commonly used as a gemstone for jewelry, lapidary arts, decorative ornaments, and historically as a material for knapping tools/arrowheads.

Geological facts

Jasper is an opaque variety of chalcedony. The red/purple hues are almost always caused by inclusions of iron oxides like hematite. It has been used by various cultures since the Bronze Age for seals and amulets.

Field identification & locations

Identify in the field by its waxy texture, opaque appearance (it does not let light through even on thin edges), and its signature conchoidal (shell-like) fracture patterns. Found globally, specifically in areas with volcanic activity or ancient seabed deposits.