mineral
Tumbled jasper or chalcedony pebble
Microcrystalline quartz, SiO₂ (likely jasper/chalcedony)
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; cream, yellow, brown, and gray coloration with opaque, subtly waxy-to-dull luster and irregular mottling. It lacks visible cleavage and consists of cryptocrystalline quartz, likely polished or naturally rounded.
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Physical properties
Hardness about 6.5–7 Mohs; cream, yellow, brown, and gray coloration with opaque, subtly waxy-to-dull luster and irregular mottling. It lacks visible cleavage and consists of cryptocrystalline quartz, likely polished or naturally rounded.
Formation & geological history
Forms when silica-rich groundwater fills cavities or replaces volcanic and sedimentary material, with iron oxides producing yellow-brown colors. The specimen’s exact geological age and locality cannot be determined from the image.
Uses & applications
Commonly used for lapidary cabochons, beads, carvings, and decorative tumbled stones; less commonly used as aggregate or ornamental stone.
Geological facts
Jasper is opaque chalcedony containing impurities, while chalcedony is generally translucent. The branching dark pattern may reflect iron-oxide staining or inclusions, but the image is insufficient for a precise variety identification.
Field identification & locations
Test for hardness against glass, inspect for a fine waxy texture, and use a strong light to check translucency; acid testing is unnecessary. Common sources include volcanic terrains in the western United States, Brazil, Madagascar, and Australia.
