Rock Identifier
Polished red/brown agate bead bracelet (Microcrystalline quartz (chalcedony), SiO₂; likely carnelian/banded agate varieties) — gemstone
gemstone

Polished red/brown agate bead bracelet

Microcrystalline quartz (chalcedony), SiO₂; likely carnelian/banded agate varieties

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent reddish, orange, brown, and gray colors with waxy to vitreous luster. Cryptocrystalline quartz has no visible cleavage and typically specific gravity near 2.6.

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Physical properties

Hardness 6.5–7 Mohs; translucent reddish, orange, brown, and gray colors with waxy to vitreous luster. Cryptocrystalline quartz has no visible cleavage and typically specific gravity near 2.6.

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and iron-stained layers over long periods, commonly during the Cenozoic or older volcanic episodes. The beads are human-cut, drilled, polished, and strung.

Uses & applications

Used for jewelry, beads, carvings, and ornamental objects; durable and inexpensive compared with precious gemstones.

Geological facts

Red coloration generally comes from iron oxides, while darker bands may reflect inclusions or different silica layers. The image appears to show a commercial mixed agate/carnelian bracelet rather than one uniform mineral specimen.

Field identification & locations

Identify by its glassy/waxy polish, hardness, translucency, and irregular internal color bands; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, India, Madagascar, and Mexico.