Rock Identifier
Brecciated jasper (Chalcedony–quartz aggregate, predominantly SiO₂, with iron-oxide coloring) — mineral
mineral

Brecciated jasper

Chalcedony–quartz aggregate, predominantly SiO₂, with iron-oxide coloring

AI-generated identification · may be incorrect

Opaque to locally translucent, reddish-brown, cream, and gray; earthy to waxy luster with angular breccia fragments and iron-oxide veining. Quartz hardness is about Mohs 6.5–7; no cleavage; specific gravity roughly 2.55–2.70.

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Physical properties

Opaque to locally translucent, reddish-brown, cream, and gray; earthy to waxy luster with angular breccia fragments and iron-oxide veining. Quartz hardness is about Mohs 6.5–7; no cleavage; specific gravity roughly 2.55–2.70.

Formation & geological history

Likely formed when silica-rich fluids cemented and replaced fractured volcanic or sedimentary rock, with hematite/goethite producing the red-brown colors. Precise age and locality cannot be determined from the photograph.

Uses & applications

Used as a lapidary material for cabochons, carvings, beads, bookends, and polished display specimens; generally unsuitable as a major construction stone.

Geological facts

Jasper is an opaque variety of microcrystalline quartz, while brecciated varieties preserve angular fragments of the original rock. Red coloration commonly reflects dispersed iron oxides rather than the quartz itself.

Field identification & locations

Identify by its very fine-grained, non-crystalline appearance, high hardness, waxy luster, and inability to scratch with a steel knife easily; a streak test is usually white to pale brown. Common sources include volcanic terrains in the western United States, Mexico, Australia, and Africa.