Agate

Agate is a stone consisting of lines of quartz and chalcedony. It is found all over the world in many varieties with many different colors. It was first used by prehistoric people about 20,000 years ago. It was known to the ancient Egyptians. The name agate was given to the stone by the ancient Greeks because it was found near the Achates River in Sicily.
Today it is used to make beautiful jewelry.
You can see an example of an agate necklace at Agatea by Beadshaper