mineral

Red jasper (tumbled river pebble)

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

AI-generated identification · may be incorrect

Typically red to brown, opaque, with a glassy-to-waxy luster; Mohs hardness 6.5–7, no visible cleavage, cryptocrystalline quartz structure, and specific gravity about 2.5–2.7. The rounded shape and wet polish indicate natural water wear or tumbling.

Identified August 10, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids cement or replace sediments and volcanic material, with iron oxides producing the red color; deposits range from Precambrian to younger ages. Common in river gravels, volcanic terrains, and sedimentary iron-rich formations.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, ornaments, and lapidary work; massive jasper has occasionally been used decoratively in architecture.

Geological facts

Its color may vary from brick red to maroon, yellow, or brown, and patterns can resemble landscapes or breccia. It is not a distinct mineral species but a trade name for opaque silica-rich rock.

Field identification & locations

Identify by its opaque red-brown color, hardness, lack of cleavage, and resistance to scratching by steel; a streak test is usually pale brownish-red. Common sources include India, Madagascar, Brazil, Australia, and the western United States.