Rock Identifier
Red jasper (polished/tumbled) (Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides) — mineral
mineral

Red jasper (polished/tumbled)

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

AI-generated identification · may be incorrect

Typically Mohs 6.5–7; brick-red to reddish brown, opaque, with a vitreous-to-waxy luster and no visible crystal faces. It is cryptocrystalline quartz with conchoidal fracture; the dark streaks may be iron-rich inclusions or brecciation.

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Physical properties

Typically Mohs 6.5–7; brick-red to reddish brown, opaque, with a vitreous-to-waxy luster and no visible crystal faces. It is cryptocrystalline quartz with conchoidal fracture; the dark streaks may be iron-rich inclusions or brecciation.

Formation & geological history

Forms when silica-rich fluids cement or replace sediments and volcanic material, with iron oxidation producing the red color. Jasper occurs in rocks ranging from Precambrian to younger ages; the specimen has been polished and its exact source cannot be determined visually.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and lapidary specimens; occasionally as decorative stone. Common polished pieces generally have modest value.

Geological facts

Red jasper is a variety of chalcedony/quartz rather than a distinct mineral species. Its color intensity and patterns depend on hematite, goethite, and other iron-bearing impurities.

Field identification & locations

Identify by its opaque red color, smooth polish, hardness, and inability to scratch with a steel blade easily; it should not fizz in dilute acid. Common sources include India, Brazil, Madagascar, the United States, and Australia.