igneous
Tumbled jasper or rhyolitic volcanic rock
Microcrystalline quartz-bearing rhyolite/jasper; commonly quartz (SiO₂), feldspar, and iron-oxide minerals
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque, rounded and polished, with tan, orange, gray-green, and reddish-brown mottling. Typically has a dull to waxy luster, no obvious cleavage, and fine-grained or cryptocrystalline texture.
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Physical properties
Hardness about 6.5–7 Mohs; opaque, rounded and polished, with tan, orange, gray-green, and reddish-brown mottling. Typically has a dull to waxy luster, no obvious cleavage, and fine-grained or cryptocrystalline texture.
Formation & geological history
Likely formed from silica-rich volcanic lava or volcanic sediment later silicified and stained by iron oxides; exact geological age cannot be determined from the photograph. Tumbled abrasion has smoothed and polished the surface.
Uses & applications
Used as an ornamental stone, cabochon, bead, paperweight, and lapidary material; attractive pieces commonly enter jasper collections.
Geological facts
The specimen’s broad color patches and apparent fine texture are consistent with jasper or altered rhyolite, but a definitive identification requires hardness, streak, density, and microscopic or chemical testing.
Field identification & locations
Common in volcanic terrains worldwide, including the western United States, Mexico, Madagascar, India, and Australia. Jasper generally leaves no streak on unglazed porcelain and should resist scratching by a steel blade.
