Agate is a cryptocrystalline variety of silica, chiefly chalcedony, characterised by its fineness of grain and brightness of color. Although agates may be found in various kinds of rock, they are classically associated with volcanic rocks and can be common in certain metamorphic rocks.
This is a gallery of Amazing Agate Photos
Amazing Agate Photos
1 of 15

Coyamito Agate Pseudomorph aka pretty rock. Photo Copyright © onebrightcrew/flickr
Coyamito Agate Pseudomorph aka pretty rock. Photo Copyright © onebrightcrew/flickr