mineral
Polished agate cabochons
Agate, a banded variety of microcrystalline quartz (SiO₂)
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; translucent brown to honey-colored, with a waxy-to-glassy luster and curved internal bands. Agate is microcrystalline and has no visible cleavage; these pieces are shaped and polished stones.
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Physical properties
Hardness 6.5–7 Mohs; translucent brown to honey-colored, with a waxy-to-glassy luster and curved internal bands. Agate is microcrystalline and has no visible cleavage; these pieces are shaped and polished stones.
Formation & geological history
Agate forms as silica-rich fluids fill cavities in volcanic rocks, depositing layers over time. Its age varies by deposit, commonly ranging from millions to hundreds of millions of years.
Uses & applications
Used for jewelry, beads, ornaments, and small carvings; agate is also collected as a decorative stone.
Geological facts
The curved, concentric bands visible in the darker piece are characteristic of agate, though lighting and polish can make bands subtle.
Field identification & locations
Look for translucent chalcedony with fine, curved or concentric bands; agate occurs worldwide, including Brazil, Uruguay, India, and the United States. The small polished pieces shown cannot be assigned to a specific locality from appearance alone.
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