mineral
Tumbled yellow-orange chalcedony (possibly yellow jasper)
Microcrystalline quartz, SiO₂; chalcedony with iron-oxide coloration
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque to slightly translucent, waxy-to-dull luster, pale yellow-orange color with reddish staining, and no visible cleavage. Its rounded shape and smooth surface indicate tumbling or natural water abrasion.
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Physical properties
Hardness about 6.5–7 Mohs; opaque to slightly translucent, waxy-to-dull luster, pale yellow-orange color with reddish staining, and no visible cleavage. Its rounded shape and smooth surface indicate tumbling or natural water abrasion.
Formation & geological history
Silica-rich groundwater deposited microcrystalline quartz in cavities or fractures, with iron oxides producing the warm color; such material commonly formed in volcanic rocks during the Cenozoic or older hydrothermal episodes.
Uses & applications
Used as a lapidary stone for tumbled specimens, cabochons, carvings, and inexpensive jewelry; also collected as decorative material.
Geological facts
Chalcedony is quartz composed of extremely fine interlocking crystals, so individual crystals are usually invisible. The specimen could also be a jasper variety if fully opaque and more granular.
Field identification & locations
Check for glassy hardness: it should scratch ordinary window glass but not quartz. Common sources include Brazil, Madagascar, India, Uruguay, and the western United States; acid testing is unnecessary.
