Rock Identifier
Tumbled red jasper (Jasper, an opaque microcrystalline variety of quartz (SiO₂), commonly colored by iron oxides) — mineral
mineral

Tumbled red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), commonly colored by iron oxides

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; brick-red to reddish brown, opaque, fine-grained, and waxy to dull with a smooth polished surface. It has no visible cleavage, conchoidal fracture, and specific gravity around 2.5–2.7.

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Physical properties

Mohs hardness 6.5–7; brick-red to reddish brown, opaque, fine-grained, and waxy to dull with a smooth polished surface. It has no visible cleavage, conchoidal fracture, and specific gravity around 2.5–2.7.

Formation & geological history

Forms when silica-rich groundwater fills and cements cavities or replaces volcanic and sedimentary rock, with iron producing the red color. Deposits occur in many geological ages, commonly in volcanic terrains and iron-rich sedimentary formations.

Uses & applications

Used for cabochons, beads, carvings, polished stones, and decorative objects; occasionally used as a minor lapidary aggregate. Its value is primarily ornamental rather than industrial.

Geological facts

Jasper is a variety of chalcedony or microcrystalline quartz, though the term is often used broadly for opaque silica-rich rocks. Tumbled jasper commonly develops rounded edges and a satin-to-glossy polish.

Field identification & locations

Identify it by its opaque red color, very fine texture, substantial weight, and inability to scratch with a steel knife easily; it should scratch glass. Common sources include India, Madagascar, Brazil, Australia, and the western United States.