sedimentary

Jasper

Jasper (Silicon Dioxide, SiO2)

Hardness: 6.5–7 (Mohs scale); Color: Yellow, orange, and brown (iron oxide inclusions); Luster: Vitreous to waxy; Crystal Structure: Microcrystalline trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.91

Hardness: 6
Color: Yellow, orange, and brown (iron oxide inclusions)
Luster: Vitreous to waxy

Identified April 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica from mineral-rich water or hydrothermal fluids, often replacing organic materials or volcanic ash. This yellow-brown variety is often called 'Yellow Jasper' or 'Ochre Jasper' and is found in various geological ages alongside quartz-rich formations.

Uses & applications

Used in lapidary arts for cabochons, beads, and ornamental stones; historically used for seals and decorative items; popular for stone tumbling and collection specimens.

Geological facts

Jasper is an opaque variety of chalcedony. Its patterns and colors are caused by up to 20% mineral inclusions, predominantly iron oxides like goethite or limonite in yellow specimens. Famous ancient seal stones were often carved from jasper due to its durability.

Field identification & locations

Identify in the field by its opacity (does not transmit light like agate), high hardness (cannot be scratched by a steel knife), and characteristic smooth, waxy surface when wet or polished. Often found in riverbeds or coastal deposits.