igneous
Tumbled purple jasper (likely rhyolite-derived jasper)
Microcrystalline quartz (SiO₂) with iron/manganese oxide impurities; possibly purple rhyolitic jasper
AI-generated identification · may be incorrectOpaque, lavender-purple, fine-grained, and waxy to dull-lustrous with conchoidal fractures; Mohs hardness about 6.5–7, no cleavage, and typical specific gravity 2.55–2.70. The rounded shape indicates tumbling or water wear, with visible surface fractures.
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Physical properties
Opaque, lavender-purple, fine-grained, and waxy to dull-lustrous with conchoidal fractures; Mohs hardness about 6.5–7, no cleavage, and typical specific gravity 2.55–2.70. The rounded shape indicates tumbling or water wear, with visible surface fractures.
Formation & geological history
Jasper forms when silica-rich volcanic fluids replace or cement volcanic ash and rock, later acquiring purple coloration from trace iron or manganese. It commonly formed in volcanic terrains during various geologic ages, rather than representing one specific age.
Uses & applications
Used as an inexpensive ornamental stone for cabochons, carvings, beads, and polished specimens; occasionally used decoratively in small slabs and mosaics.
Geological facts
Jasper is an opaque variety of chalcedony or microcrystalline quartz, unlike amethyst, which is transparent to translucent crystalline quartz. Purple coloration can overlap with lavender rhyolite, sugilite-like material, or dyed stone.
Field identification & locations
Identify by its opaque purple color, very fine texture, hardness, and inability to scratch it with a steel knife easily; glass should be scratchable only with difficulty. Common sources include volcanic regions of the western United States, Madagascar, Brazil, and Australia.
