mineral
Banded agate (likely carnelian/chalcedony)
Microcrystalline quartz (SiO₂), chalcedony; banded variety
AI-generated identification · may be incorrectWaxy to vitreous luster, translucent gray-white and reddish-brown bands; Mohs hardness 6.5–7, trigonal quartz structure, no cleavage, conchoidal fracture. The small, worn specimen makes precise identification uncertain.
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Physical properties
Waxy to vitreous luster, translucent gray-white and reddish-brown bands; Mohs hardness 6.5–7, trigonal quartz structure, no cleavage, conchoidal fracture. The small, worn specimen makes precise identification uncertain.
Formation & geological history
Silica-rich fluids deposited successive layers in a rock cavity, later hardened into agate; agates form in many geological ages, commonly in volcanic rocks.
Uses & applications
Used for beads, cabochons, carvings, ornaments, and small decorative specimens; industrial chalcedony is also used for durable objects.
Geological facts
Agate’s fine color bands record changing silica deposition; reddish coloration commonly comes from iron oxides.
Field identification & locations
Look for curved or concentric bands, waxy luster, and hardness sufficient to scratch glass; common in volcanic regions and stream gravels worldwide. This appears naturally worn rather than highly polished.
