mineral
Polished banded jasper
Jasper, microcrystalline quartz (SiO₂) with iron-oxide inclusions
AI-generated identification · may be incorrectOpaque, dark reddish-brown and cream mottling with a waxy-to-dull luster; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and a dense, cryptocrystalline structure. The rounded surface indicates tumbling or water wear.
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Physical properties
Opaque, dark reddish-brown and cream mottling with a waxy-to-dull luster; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and a dense, cryptocrystalline structure. The rounded surface indicates tumbling or water wear.
Formation & geological history
Forms when silica-rich fluids replace or cement volcanic ash, sediment, or other rock, with iron oxides producing the red-brown colors. Jasper deposits range from Precambrian to recent and commonly occur in volcanic and sedimentary terrains.
Uses & applications
Used for cabochons, beads, carvings, ornamental objects, and polished display stones; it has little industrial value compared with ordinary quartz.
Geological facts
Jasper is a variety of opaque chalcedony or microcrystalline quartz, and its patterns are produced by mineral impurities rather than large crystals. The specimen may also be marketed as brown or scenic jasper.
Field identification & locations
Identify it by its opaque appearance, fine texture, quartz-like hardness, and resistance to scratching by steel; a streak test is usually white to colorless. Common sources include India, Madagascar, Brazil, Australia, and the western United States.
