sedimentary

Jasper (specifically a banded or dark variety)

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5 - 7 on the Mohs scale; Color: Dark grey to black with brownish-tan bands; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58 - 2.91

Hardness: 6
Color: Dark grey to black with brownish-tan bands
Luster: Vitreous to waxy

Identified February 20, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica from water or volcanic ash, occurring in many geological ages from the Precambrian to more recent times. It often forms through chemical precipitation or the replacement of organic matter.

Uses & applications

Used primarily in lapidary work for making cabochons, beads, and jewelry. It is also a popular specimen for rock hounds and collectors due to its hardness and ability to take a high polish.

Geological facts

Jasper is a variety of chalcedony. The name comes from the Greek 'iaspis', meaning spotted stone. It has been used for centuries for seals, talismans, and ornamental objects across many cultures.

Field identification & locations

Identify in the field by its hardness (it will scratch glass/steel but cannot be scratched by a knife), smooth conchoidal fracture, and opaque appearance. It is commonly found in gravel pits, riverbeds, and areas with volcanic activity or ancient sedimentary basins.

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