sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, earthy tones; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown, earthy tones
Luster: Vitreous to dull

Identified June 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from water-saturated solutions in volcanic ash or hydrothermal veins. Often associated with the replacement of organic materials or sedimentary accumulation over millions of years.

Uses & applications

Used primarily in lapidary work for jewelry, cabochons, and decorative carvings. Historically used for making tools and seals due to its toughness and fracture pattern.

Geological facts

Jasper is an opaque variety of chalcedony. The reddish color is typically caused by iron inclusions. It has been a featured gemstone in religious texts and ancient Mesopotamian cylinder seals.

Field identification & locations

Identify in the field by its opacity (it does not pass light even on thin edges), its hardness (will scratch glass), and its distinctive waxy/smooth feel when broken. Found globally in areas with volcanic or sedimentary history.