mineral
Tumbled chalcedony (likely orange agate/carnelian)
Microcrystalline quartz, SiO₂; chalcedony with iron-oxide coloration
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; translucent honey-orange to cream, with waxy-to-glassy luster and no visible cleavage. Its rounded shape and polished surface indicate human tumbling; pale patches may be quartz, druzy, or matrix.
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Physical properties
Hardness 6.5–7 Mohs; translucent honey-orange to cream, with waxy-to-glassy luster and no visible cleavage. Its rounded shape and polished surface indicate human tumbling; pale patches may be quartz, druzy, or matrix.
Formation & geological history
Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, often developing banding or iron staining; many deposits formed during the Cenozoic, though chalcedony occurs throughout geological time.
Uses & applications
Used for cabochons, beads, carvings, ornamental stone, and inexpensive jewelry; polished pieces are also popular as decorative and metaphysical specimens.
Geological facts
Carnelian is the orange-red variety of chalcedony, while agate is typically banded or patterned chalcedony; the boundary between the names can be informal.
Field identification & locations
Common in volcanic terrains and gravels worldwide, especially Brazil, Uruguay, India, Madagascar, and the western United States. A glassy/waxy surface, quartz-like hardness, translucency, and lack of cleavage help distinguish it from colored glass.
