sedimentary

Red Jasper (Chert)

Silicon Dioxide (SiO2) with impure Iron Oxides

Hardness: 6.5-7 (Mohs scale), Color: Opaque reddish-brown due to iron inclusions, Luster: Vitreous to waxy, Crystal Structure: Trigonal (microcrystalline/cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.91

Hardness: 6

Identified May 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica in sedimentary or volcanic environments, typically as nodules or veins. Its coloration is primarily due to the presence of hematite or other iron-rich minerals deposited during the silica precipitation process over millions of years.

Uses & applications

Commonly used for lapidary work including cabochons, beads, and carved figurines. It is often employed as an ornamental stone in jewelry, as well as for decorative items like bookends or mosaic tiles.

Geological facts

Jasper has been used as a gemstone since antiquity and is mentioned in various historical texts, including the Bible. The name jasper comes from the Greek word 'iaspis', meaning 'spotted stone'. It is a variety of chalcedony.

Field identification & locations

Identify in the field by its distinct conchoidal (shell-like) fracture, high hardness (cannot be scratched by a steel knife), and its absolute opacity. It is commonly found in gravel beds of rivers or in arid desert regions in the USA (Oregon, California, Idaho), India, and Brazil.

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