sedimentary

Jasper

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Reddish-brown (due to iron inclusions); Luster: Vitreous to waxy; Crystal Structure: Microcrystalline/Cryptocrystalline (Trigonal); Cleavage: None; Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown (due to iron inclusions)
Luster: Vitreous to waxy

Identified March 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments. It often forms through a process called silicification during sedimental deposition in ancient seabed environments. Age varies by location but can date back hundreds of millions of years.

Uses & applications

Used primarily as decorative gemstones for jewelry (cabochons), interior ornamentation, mosaics, and as a popular specimen for rock tumbling and metaphysical collections.

Geological facts

Jasper is an opaque variety of chalcedony. The name 'Jasper' is derived from the Greek for 'spotted stone.' It has been a popular gemstone since antiquity, mentioned in diverse historical texts including the Bible and ancient Greek Lapidaries.

Field identification & locations

Identify in the field by its smooth, waxy surface and conchoidal (shell-like) fracture. Unlike other stones, it is fully opaque even when held to a strong light. Commonly found in riverbeds, glacial tills, and desert regions globally. Notable locations include the USA, India, Russia, and Brazil.