mineral
Polished brecciated jasper
Jasper, microcrystalline quartz (SiO₂), commonly containing hematite, goethite, and clay minerals
AI-generated identification · may be incorrectOpaque, multicolored brown, red, cream, gray, and black fragments in a brecciated pattern; waxy to vitreous luster when polished; Mohs hardness about 6.5–7; no visible cleavage; cryptocrystalline quartz structure; specific gravity approximately 2.5–2.7.
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Physical properties
Opaque, multicolored brown, red, cream, gray, and black fragments in a brecciated pattern; waxy to vitreous luster when polished; Mohs hardness about 6.5–7; no visible cleavage; cryptocrystalline quartz structure; specific gravity approximately 2.5–2.7.
Formation & geological history
Silica-rich fluids cemented and replaced fractured volcanic or sedimentary material, with iron oxides producing the red-brown colors. Formation ages vary widely, commonly Paleozoic to Precambrian depending on locality.
Uses & applications
Used for cabochons, beads, carvings, polished display pieces, and lapidary objects; occasionally used as decorative stone and minor facing material.
Geological facts
Jasper is a variety of opaque chalcedony or microcrystalline quartz. Brecciation—the angular fragments and contrasting cement—is a key visual feature, while iron minerals create natural pictorial patterns.
Field identification & locations
Identify by its opacity, hardness, fine-grained texture, and resistance to scratching; it should not show large quartz crystals. Common sources include Madagascar, India, Brazil, Australia, and the western United States.
