mineral
Tumbled carnelian/chalcedony
Cryptocrystalline quartz, SiO₂ (iron-bearing chalcedony)
AI-generated identification · may be incorrectGlossy, polished reddish-brown to orange material with lighter translucent patches and waxy luster. Quartz hardness is about 6.5–7 Mohs; no visible cleavage, conchoidal fracture, and specific gravity near 2.6. The blue-white reflections are likely surface glare, not blue mineral zones.
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Physical properties
Glossy, polished reddish-brown to orange material with lighter translucent patches and waxy luster. Quartz hardness is about 6.5–7 Mohs; no visible cleavage, conchoidal fracture, and specific gravity near 2.6. The blue-white reflections are likely surface glare, not blue mineral zones.
Formation & geological history
Forms when silica-rich groundwater fills cavities and fractures, with iron oxides producing the red-brown color; later weathering releases rounded pieces. Chalcedony commonly formed in volcanic rocks during the Cenozoic, though the specimen’s exact age and source cannot be determined visually.
Uses & applications
Used for beads, cabochons, carvings, and ornamental objects; polished pieces are inexpensive collectibles.
Geological facts
Carnelian is the orange-red variety; darker brown-red material is often called sard or iron-stained chalcedony. Color may be naturally enhanced or heat-treated.
Field identification & locations
Identify by its even cryptocrystalline texture, glassy-to-waxy polish, hardness, and conchoidal fracture. Around 47.6°N, 19.3°E, transported chalcedony/carnelian gravel is plausible, although the exact locality is uncertain.
