sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5–7 on Mohs scale; Color: Reddish-brown, tan, and earthy tones; Luster: Dull to waxy; Crystal structure: Microcrystalline (trigonal); Cleavage: None, exhibits conchoidal (shell-like) fracture; Specific Gravity: 2.58–2.91

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

Identified April 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica from water or hydrothermal fluids into sediments or volcanic ash. The red and brown colors are primarily due to iron oxide impurities (hematite or goethite). It is often found in prehistoric sedimentary deposits.

Uses & applications

Used primarily for lapidary work, jewelry (cabochons), river rock landscaping, and as a decorative stone for collectors.

Geological facts

Jasper has been used for thousands of years as a gemstone and for tool-making; it was even used in the ancient world for seals and amulets. Because it is a form of chalcedony, it is incredibly durable and holds a high polish.

Field identification & locations

Identify in the field by its smooth, water-worn texture, its hardness (it can scratch glass), and its lack of transparency (unlike agate). Common in river beds, deserts, and glacial deposits. For collectors, look for patterns or banding.