metamorphic
Polished brecciated jasper
Silica-rich microcrystalline quartz/chalcedony (SiO₂), with iron-oxide staining and angular mineral fragments
AI-generated identification · may be incorrectTypically Mohs 6.5–7, opaque, fine-grained, and waxy to glassy when polished; this specimen is charcoal-gray with a rusty red-brown breccia-like patch. Quartz has no cleavage, conchoidal fracture, and specific gravity around 2.6.
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Physical properties
Typically Mohs 6.5–7, opaque, fine-grained, and waxy to glassy when polished; this specimen is charcoal-gray with a rusty red-brown breccia-like patch. Quartz has no cleavage, conchoidal fracture, and specific gravity around 2.6.
Formation & geological history
Forms when silica-rich material, commonly volcanic or sedimentary rock, is fractured and later cemented by chalcedony or quartz, with iron oxides producing red-brown colors. Formation ages vary widely, commonly Paleozoic to Cenozoic depending on deposit.
Uses & applications
Used for cabochons, beads, carvings, ornaments, and lapidary objects; architectural use is limited because jasper commonly occurs in small irregular pieces. Collecting value is mainly determined by pattern, polish, and workmanship.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz; “brecciated” describes its angular fragment pattern rather than a separate mineral species.
Field identification & locations
Identify it by its opaque appearance, strong polish, quartz-like hardness, lack of cleavage, and resistance to scratching by a steel knife; it commonly occurs in volcanic terrains, hydrothermal veins, and silica-rich sedimentary beds. Exact locality cannot be determined from the image alone.
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