metamorphic
Polished or tumbled jasper
Microcrystalline quartz (SiO₂), commonly iron-oxide-rich jasper
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque tan, cream, brown, gray, and black with irregular breccia-like patterns; glassy to waxy luster after polishing; cryptocrystalline quartz with no visible cleavage, conchoidal fracture, and specific gravity around 2.6.
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Physical properties
Hardness about 6.5–7 Mohs; opaque tan, cream, brown, gray, and black with irregular breccia-like patterns; glassy to waxy luster after polishing; cryptocrystalline quartz with no visible cleavage, conchoidal fracture, and specific gravity around 2.6.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement sediments, volcanic ash, or brecciated rock, with iron and manganese producing the colors. Formation ages vary widely, commonly Paleozoic to Cenozoic depending on locality.
Uses & applications
Used for cabochons, beads, carvings, ornamental stones, and lapidary pieces; occasionally used as decorative aggregate or facing stone.
Geological facts
The specimen may be marketed as picture jasper, brecciated jasper, or scenic jasper, although exact trade names require locality information. The contrasting veins and patches are typical of iron-stained silica replacement.
Field identification & locations
Identify by its opaque, fine-grained texture, strong polish, hardness, and lack of cleavage; it should resist scratching by a steel blade. Common sources include Oregon, Idaho, Utah, California, Mexico, Madagascar, and Australia.
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