Rock Identifier
Tumbled jasper (likely picture/brecciated jasper) (Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides) — mineral
mineral

Tumbled jasper (likely picture/brecciated jasper)

Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides

AI-generated identification · may be incorrect

Opaque reddish-brown and cream mottling, earthy to waxy luster, conchoidal fracture, no visible cleavage; hardness about 6.5–7 Mohs and specific gravity ~2.6. The rounded shape indicates tumbling or natural abrasion.

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Physical properties

Opaque reddish-brown and cream mottling, earthy to waxy luster, conchoidal fracture, no visible cleavage; hardness about 6.5–7 Mohs and specific gravity ~2.6. The rounded shape indicates tumbling or natural abrasion.

Formation & geological history

Forms when silica-rich fluids fill cavities or replace volcanic and sedimentary material, with iron producing red-brown coloration; typically Phanerozoic but age depends on locality. Common in volcanic terrains and silica-rich sedimentary deposits.

Uses & applications

Used for cabochons, beads, carvings, polished stones, and decorative objects; common tumbled material has modest value.

Geological facts

Jasper is a variety of opaque chalcedony rather than a separate mineral species. Patterns arise from brecciation, sedimentary layering, or iron-rich mineral inclusions.

Field identification & locations

Identify by its dense opaque body, red-brown/cream patterns, glassy-waxy luster, and resistance to scratching; quartz or steel should not easily scratch it. Common sources include Oregon, Idaho, Utah, Madagascar, Brazil, and Australia.