metamorphic
Polished brecciated jasper
Jasper: microcrystalline quartz (SiO₂) with iron-oxide and other mineral inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque, reddish-brown, golden, gray, and black coloration with a vitreous-to-waxy polish. It has cryptocrystalline quartz structure, no visible cleavage, and typical specific gravity near 2.6.
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Physical properties
Hardness about 6.5–7 Mohs; opaque, reddish-brown, golden, gray, and black coloration with a vitreous-to-waxy polish. It has cryptocrystalline quartz structure, no visible cleavage, and typical specific gravity near 2.6.
Formation & geological history
Forms when silica-rich fluids cement or replace volcanic ash, sediment, or fractured rock, with iron oxides producing the red and brown colors; many deposits are Paleozoic to Cenozoic, though age varies by locality.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; durable varieties have minor architectural and decorative uses.
Geological facts
The irregular color patches and vein-like boundaries suggest brecciation, while the glossy surface indicates tumbling or polishing. Jasper is a variety of chalcedony/microcrystalline quartz rather than a single precisely defined mineral species.
Field identification & locations
Identify it by its opaque appearance, strong red-brown iron staining, hardness, and inability to scratch with a steel knife easily; common sources include India, Madagascar, Brazil, Australia, and the western United States.
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