Rock Identifier
Polished/tumbled brecciated jasper (Silica-rich microcrystalline quartz (chalcedony), commonly with iron-oxide minerals and assorted lithic fragments) — sedimentary
sedimentary

Polished/tumbled brecciated jasper

Silica-rich microcrystalline quartz (chalcedony), commonly with iron-oxide minerals and assorted lithic fragments

AI-generated identification · may be incorrect

Typically opaque, multicolored gray, blue, tan, red, and brown with a waxy to dull luster and irregular breccia-like patterning; hardness about 6.5–7 Mohs, no cleavage, and specific gravity near 2.6. The rounded shape indicates tumbling or natural abrasion.

Identified More sedimentary
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Physical properties

Typically opaque, multicolored gray, blue, tan, red, and brown with a waxy to dull luster and irregular breccia-like patterning; hardness about 6.5–7 Mohs, no cleavage, and specific gravity near 2.6. The rounded shape indicates tumbling or natural abrasion.

Formation & geological history

Forms when silica-rich fluids cement fragments of older volcanic or sedimentary rocks, often incorporating hematite or limonite that produces red, gold, and brown colors. Jasper deposits range from Precambrian to much younger ages and occur in volcanic and sedimentary environments.

Uses & applications

Used for cabochons, beads, carvings, polished stones, and lapidary collectibles; occasionally used decoratively in mosaics and small ornaments.

Geological facts

Jasper is a variety of opaque chalcedony rather than a single mineral species. Brecciated varieties are especially valued for their contrasting angular fragments and iron-rich color patterns.

Field identification & locations

Identify it by its opaque appearance, fine-grained texture, glassy-to-waxy polish, and inability to scratch with a steel knife; quartz or glass can scratch it. Common sources include India, Madagascar, Mexico, Brazil, Australia, and the western United States.