sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Pale green, tan, and brown with dark speckles; Luster: Dull to waxy; Crystal Structure: Microcrystalline (trigonal); Cleavage: None; Specific Gravity: 2.58-2.91

Hardness: 6
Color: Pale green, tan, and brown with dark speckles
Luster: Dull to waxy

Identified May 5, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Pale green, tan, and brown with dark speckles; Luster: Dull to waxy; Crystal Structure: Microcrystalline (trigonal); Cleavage: None; Specific Gravity: 2.58-2.91

Formation & geological history

Formed from silica-rich fluids permeating volcanic ash or sedimentary deposits, often under low temperature and pressure. The specimen shows significant rounded tumbling from river or coastal water erosion.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and ornamental carvings. Lower quality specimens like this are collected as pocket stones or aquarium gravel.

Geological facts

Jasper is an opaque variety of chalcedony. The grainy texture and patterns are caused by impurities; in this case, iron oxides or manganese likely create the dark dendritic or spotted patterns.

Field identification & locations

Identify by its hardness (cannot be scratched by a steel knife) and smooth, water-worn exterior. Commonly found in riverbeds and on beaches worldwide. Collectors look for unique patterns or bright colors.