mineral
Polished brecciated jasper
Jasper, an opaque microcrystalline variety of chalcedony (SiO₂), with iron-oxide staining
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque red, orange, cream, and purple-brown colors with brecciated patterns; vitreous to waxy luster and no visible cleavage. The pale areas may be quartz/chalcedony or altered host rock.
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Physical properties
Hardness about 6.5–7 Mohs; opaque red, orange, cream, and purple-brown colors with brecciated patterns; vitreous to waxy luster and no visible cleavage. The pale areas may be quartz/chalcedony or altered host rock.
Formation & geological history
Forms when silica-rich groundwater replaces or cements fractured volcanic or sedimentary material, with iron oxides producing the red coloration. Deposits are generally geologically ancient, commonly Paleozoic to Cenozoic depending on locality.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, ornamental objects, and collector specimens; too opaque and patterned for faceted gemstone use.
Geological facts
Jasper is technically a rock or rock-like aggregate rather than a single pure mineral. “Brecciated” describes the angular fragments cemented together by silica and/or iron-rich material.
Field identification & locations
Identify it by its opaque appearance, vivid iron-red colors, irregular fragment-like pattern, and ability to scratch glass; it should not fizz in dilute hydrochloric acid. Common sources include Oregon, Idaho, Utah, Madagascar, Brazil, India, and Australia.
