sedimentary

Jasper

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown, earthy tones; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown, earthy tones
Luster: Dull to waxy

Identified July 4, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown, earthy tones; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments, commonly occurring in sedimentary environments through a process of replacement or precipitation over millions of years.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and carvings. Historically used for seals and amulets. Small rounded specimens are popular in rock tumbling.

Geological facts

Jasper is an opaque variety of chalcedony. The reddish-brown color is typically caused by the presence of iron oxide (hematite) inclusions within the silica structure.

Field identification & locations

Identify in the field by its hardness (survives scratching with a steel file), opaque nature, and smooth, waxy feel when worn by water. Found worldwide, especially in gravel beds and ancient volcanic regions.