Agate

Banding that moves slow, like time marked in stone.

Stone

Chalcedony (quartz)

Major Sources

Brazil, Uruguay, Mexico & Botswana

Treatment

Often dyed; ours undyed

Agate is banded chalcedony, a fine-grained quartz that fills cavities in volcanic rock one silica layer at a time. It's sold as raw nodules, geodes, slices and tumbled stones. Bright, flat pinks, blues and purples are usually dyed, while natural agate shows soft, layered color.