sedimentary

Jasper (Chert)

SiO2 (Microcrystalline Quartz with Iron Oxide impurities)

AI-generated identification · may be incorrect

Hardness: 6.5 - 7 on Mohs scale. Color: Reddish-brown, yellow-brown, earth tones. Luster: Vitreous to dull, smooth when wet or polished. Crystal Structure: Trigonal/Microcrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.58 - 2.91.

Hardness: 6
Color: Reddish-brown, yellow-brown, earth tones
Luster: Vitreous to dull, smooth when wet or polished

Identified July 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when fine microcrystalline quartz (chert) precipitates from hydrothermal fluids or marine sedimentary environments, enriched with hematite or goethite iron oxides that give it its reddish-brown color. Found frequently in coastal and river deposits after being weathered out of parent rocks.

Uses & applications

Used in lapidary arts, jewelry making, cabochons, tumbled decorative stones, and rock collecting. Historically used for making tools and arrowheads due to its conchoidal fracturing properties.

Geological facts

Jasper gets its signature red-brown tone from inclusions of iron minerals. Because of its hardness and fine grain, beach-tumbled jasper can naturally develop a smooth, polished sheen from the abrasive action of water and sand.

Field identification & locations

Identified by its rich reddish-brown color, opacity (does not let light pass through like agate does), and strong resistance to scratching. Look for it along ocean beaches, river beds, and gravel bars in volcanic or sedimentary regions.