metamorphic
Leopard skin jasper (orbicular jasper)
Microcrystalline quartz (SiO₂), commonly with iron-oxide and other silicate inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; gray-white matrix with dark brown to black branching or orbicular patterns, opaque, and waxy to dull luster. It is cryptocrystalline quartz with no visible cleavage and a conchoidal fracture.
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Physical properties
Hardness about 6.5–7 Mohs; gray-white matrix with dark brown to black branching or orbicular patterns, opaque, and waxy to dull luster. It is cryptocrystalline quartz with no visible cleavage and a conchoidal fracture.
Formation & geological history
Forms when silica-rich volcanic or sedimentary material is replaced and recrystallized by groundwater, with iron and manganese producing the dark markings. Deposits are generally geologically young to Mesozoic–Cenozoic, depending on locality.
Uses & applications
Used for cabochons, beads, carvings, polished stones, and collector specimens; occasionally used decoratively. It has modest gem-market value unless the pattern and polish are exceptional.
Geological facts
The pictured material may also be called Picasso jasper or a patterned jasper, though exact naming requires locality information. Jasper is technically an opaque variety of chalcedony/microcrystalline quartz.
Field identification & locations
Identify it by its opaque fine grain, quartz-like hardness, lack of cleavage, and distinctive dark network pattern; common sources include Madagascar, Mexico, Indonesia, and the western United States. A streak and hardness test can help distinguish it from painted or artificial material.
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