metamorphic
Polished orbicular jasper (likely leopard-skin or brecciated jasper)
Microcrystalline quartz (SiO₂) with iron-oxide minerals; exact variety uncertain from the image
AI-generated identification · may be incorrectOpaque black-to-orange, rounded and polished, with a fine cryptocrystalline texture and earthy-to-waxy luster; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and typical specific gravity near 2.6.
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Physical properties
Opaque black-to-orange, rounded and polished, with a fine cryptocrystalline texture and earthy-to-waxy luster; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and typical specific gravity near 2.6.
Formation & geological history
Jasper forms when silica-rich fluids replace or cement volcanic, sedimentary, or brecciated material, while iron oxides create the orange coloration. It commonly formed in ancient volcanic environments, often during Precambrian to younger geologic episodes.
Uses & applications
Used as a cabochon, tumbled stone, ornamental object, and collector specimen; rarely used as minor decorative stone or aggregate.
Geological facts
The orange patches are probably hematite or goethite, whereas the dark matrix is silica-rich jasper or volcanic material. Strongly consistent patterns can indicate orbicular jasper, but photography alone cannot confirm the locality or variety.
Field identification & locations
Common sources include Madagascar, Mexico, Indonesia, Australia, and the western United States. Field clues are opaque color, glassy-to-waxy polish, hardness sufficient to scratch glass, and lack of fizz in dilute acid; a streak, loupe, and locality are needed for reliable identification.
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