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Did you know there are dozens of different types of agates, not just the few colored variations you find at the river or lake when you go agate hunting.
Agate is a see-through chalcedony. You can basically see through an agate, if you put something close enough on the other side, although it will be blurry.
A lot of agates are distinguished by having bands, plumeshaped inclusions, dendritic forms inside, or mossy looking inclusions.
You can read up on agates at GeologyPage, Wikipedia, Rock Tumbler, and Geologyin, who make a great chart.
