metamorphic
Tumbled jasper pebble
Microcrystalline quartz (SiO₂), commonly with iron-oxide inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque tan to golden-brown with mottled rusty patches and a subdued waxy-to-vitreous polish. Massive, cryptocrystalline structure with no visible cleavage; specific gravity about 2.6.
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Physical properties
Hardness about 6.5–7 Mohs; opaque tan to golden-brown with mottled rusty patches and a subdued waxy-to-vitreous polish. Massive, cryptocrystalline structure with no visible cleavage; specific gravity about 2.6.
Formation & geological history
Likely formed as silica-rich volcanic or sedimentary material later altered and impregnated by iron oxides, then naturally or mechanically rounded and polished. Jasper deposits range from Precambrian to recent geological ages.
Uses & applications
Used for cabochons, beads, carvings, lapidary ornaments, and decorative stone; it has little industrial value compared with quartz aggregate.
Geological facts
Jasper is a variety of opaque chalcedony or microcrystalline quartz, and its colors commonly reflect hematite or limonite. The smooth shape indicates tumbling or prolonged water abrasion.
Field identification & locations
Identify it by its opacity, fine-grained texture, lack of cleavage, earthy mottling, and ability to scratch glass; it should not fizz in dilute acid. Common sources include Oregon, Idaho, California, Brazil, India, and Australia.
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