Agate JewelryWhere the name comes from: Named by the Greek philosopher Theophrastus for the Achates River - now known as the Dirillo in Sicily.
Where the stones come from: Found worldwide.
Chemistry: Silicon dioxide, SiO2
Colors: All colours, blue and green rather rare.
...and another thing: Agates form by filling voids in host rocks. The making of and collecting of agate bowls has been popular with royalty and the rich through the ages.