sedimentary/mineral

Jasper (brecciated or orbicular variety)

Silicon dioxide (SiO2) with iron oxide inclusions

Hardness: 6.5-7 (Mohs scale); Color: Reddish-brown, yellow, ochre; Luster: Dull to greasy (waxy when wet/polished); Crystal structure: Microcrystalline quartz (Trigonal); Cleavage: None/Conchoidal fracture; Specific gravity: 2.58–2.91.

Hardness: 6
Color: Reddish-brown, yellow, ochre
Luster: Dull to greasy (waxy when wet/polished)

Identified April 8, 2026More sedimentary/mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich fluids in volcanic ash or sedimentary beds. The brecciated texture suggests it was broken and then re-cemented by later silica. Colors are caused by high iron (hematite or goethite) content.

Uses & applications

Used primarily for lapidary work, jewelry (cabochons), ornamental decoration, and as a popular specimen for rock tumbling and collecting.

Geological facts

Jasper is an opaque variety of chalcedony. Historically, it was known as the 'supreme nurturer' in ancient cultures and was often used for cylinder seals and amulets in Mesopotamia.

Field identification & locations

Identify in the field by its hardness (will scratch glass), opaque nature (unlike agate), and smooth, rounded water-worn exterior often found in riverbeds or gravel deposits. Common in regions with ancient volcanic or sedimentary activity.

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