mineral
Orange chalcedony / quartz-rich cobble
Microcrystalline quartz (SiO₂), likely iron-oxide-stained chalcedony; exact identification requires testing
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; orange-brown, opaque to weakly translucent, with dull to waxy luster and no obvious cleavage. The rounded form suggests a naturally weathered or tumbled specimen; color likely comes from hematite or goethite inclusions.
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Physical properties
Hardness about 6.5–7 Mohs; orange-brown, opaque to weakly translucent, with dull to waxy luster and no obvious cleavage. The rounded form suggests a naturally weathered or tumbled specimen; color likely comes from hematite or goethite inclusions.
Formation & geological history
Silica-rich groundwater deposited microcrystalline quartz in cavities or fractures, followed by iron staining and abrasion; commonly Cenozoic or older, depending on source rock. It may also be a polished/tumbled jasper-like quartz specimen.
Uses & applications
Used as a lapidary material for cabochons, carvings, beads, and decorative stones; attractive pieces are collected, but this example appears common-grade.
Geological facts
A steel file or quartz crystal should not easily scratch it, while glass can be scratched by it. Strong orange-red streaking or magnetic response would indicate abundant iron oxides.
Field identification & locations
Common in weathered volcanic terrains, hydrothermal veins, river gravels, and jasper deposits worldwide, including Brazil, India, Madagascar, and the western United States. Confirm with hardness, translucency, and a fresh break; avoid destructive tests on valuable pieces.
