sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5–7 on Mohs scale. Color: Greenish-brown and tan with mottled patterns. Luster: Dull to waxy. Crystal Structure: Microcrystalline/cryptocrystalline (trigonal). Cleavage: None; exhibits conchoidal fracture. Specific Gravity: 2.58–2.91.

Hardness: 6
Color: Greenish-brown and tan with mottled patterns
Luster: Dull to waxy

Identified March 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich solutions in sedimentary environments or volcanic ash. The color variations result from mineral inclusions like iron oxides or silicates during the consolidation process. Ages vary from Precambrian to Cenozoic.

Uses & applications

Commonly used in lapidary work for cabochons, beads, and ornamental carvings. Historically used for making tools and seals. Industrial use includes minor abrasive applications.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek 'iaspis', meaning 'spotted stone'. It was one of the stones in the High Priest's breastplate in biblical times.

Field identification & locations

Identify in the field by its opacity (it does not transmit light even on thin edges), its hardness (can scratch glass), and its distinctive smooth, shell-like fracture pattern. Often found in riverbeds or gravel deposits.