metamorphic
Red jasper (polished/cut rough)
Jasper, microcrystalline quartz (SiO₂), colored mainly by iron oxides
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque brick-red to reddish-brown with cream quartz/chalcedony patches, earthy to vitreous luster, cryptocrystalline structure, and no obvious cleavage. The irregular white areas may be quartz, calcite, or brecciated host material.
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Physical properties
Hardness about 6.5–7 Mohs; opaque brick-red to reddish-brown with cream quartz/chalcedony patches, earthy to vitreous luster, cryptocrystalline structure, and no obvious cleavage. The irregular white areas may be quartz, calcite, or brecciated host material.
Formation & geological history
Jasper forms when silica-rich fluids cement or replace sediments and volcanic material, commonly producing brecciated patterns; iron oxidation creates the red color. It occurs in rocks ranging from Precambrian to younger geologic ages.
Uses & applications
Used for cabochons, carvings, beads, bookends, ornaments, and polished decorative stone; occasionally used as aggregate or facing material.
Geological facts
Jasper is a variety of opaque chalcedony/microcrystalline quartz rather than a single mineral species. Brecciated red jasper is often marketed as “red jasper” even when mixed with quartz or calcite.
Field identification & locations
Identify it by its opaque red color, patchy/brecciated pattern, waxy-to-glassy luster, and resistance to scratching by a steel knife; it should not scratch glass easily unless quartz-rich. Common sources include India, Madagascar, Brazil, the United States, and Australia.
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