mineral
Tumbled jasper
Jasper, an opaque microcrystalline variety of quartz (SiO₂), commonly chalcedony with iron-oxide impurities
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; reddish-brown to ochre coloration, opaque, waxy to vitreous luster, and no visible cleavage. The smooth rounded surface indicates mechanical tumbling and polishing.
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Physical properties
Hardness about 6.5–7 Mohs; reddish-brown to ochre coloration, opaque, waxy to vitreous luster, and no visible cleavage. The smooth rounded surface indicates mechanical tumbling and polishing.
Formation & geological history
Forms when silica-rich groundwater fills cavities or replaces volcanic and sedimentary material, with iron oxides producing the brown-red colors. Deposits occur in many geologic ages, commonly in volcanic terrains.
Uses & applications
Used for cabochons, beads, carvings, ornaments, and inexpensive lapidary specimens; occasionally used as decorative stone.
Geological facts
Jasper is technically a rock rather than a single pure mineral because it contains microcrystalline quartz plus impurities and minor accessory minerals.
Field identification & locations
Identify it by its opaque fine-grained texture, earthy red-brown color, waxy polish, and inability to scratch with a steel knife; quartz should scratch glass. Common sources include India, Madagascar, Brazil, Mexico, and the United States.
