metamorphic
Red-and-black jasper
Jasper, an opaque microcrystalline quartz variety (SiO₂), colored by iron oxides
AI-generated identification · may be incorrectTypically Mohs 6.5–7; opaque brick-red and charcoal-gray, with dull to waxy luster and no visible cleavage. The rounded edges and smooth surface indicate a tumbled or polished specimen.
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Physical properties
Typically Mohs 6.5–7; opaque brick-red and charcoal-gray, with dull to waxy luster and no visible cleavage. The rounded edges and smooth surface indicate a tumbled or polished specimen.
Formation & geological history
Forms from silica-rich sediment or volcanic material later replaced and cemented by microcrystalline quartz, with hematite producing the red coloration; ages vary widely, commonly Paleozoic to Precambrian. It occurs in hydrothermal veins, volcanic terrains, and silicified sedimentary layers.
Uses & applications
Used for ornamental objects, cabochons, beads, carvings, countertops, and lapidary specimens. Common pieces have modest jewelry and collector value.
Geological facts
Jasper is technically a rock rather than a single mineral, and its patterns reflect fluctuating iron-oxide and silica deposition. Red-and-black varieties may be marketed as brecciated jasper, Picasso jasper, or hematite jasper depending on pattern and locality.
Field identification & locations
Identify it by its opaque appearance, red hematite-rich zones, gray-black quartz-rich matrix, lack of cleavage, and resistance to scratching by steel. Common sources include India, Madagascar, Brazil, the United States, and Australia.
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