Agate

Agate is also known as chalcedony. The stone was given its name by a Greek philosopher and naturalist Theophrastus, who discovered the stone along the shore line of the river Achates. The agate has been recovered at a number of ancient sites, indicating its widespread use in the ancient world.

It is a stone that has been used for centuries as gems and as precious materials for the production of ornaments or small sculptures. The name chalcedony comes from Calcedon, or Calchedon, an ancient port on the Sea of Marmara, in Asia Minor. Ornamental materials used to be mined in that area and it was an active trading center for many gems. Various forms of agate used to be used extensively for bases and handles of gold items such as goblets, and for stone inlay work.

Tiny crystals of quartz interlock to form agate and because of this, it is always opaque to translucent. Agate is an excellent material for cameos as the contrast between the different layers is used to heighten the relief. Agate's value was quite high in antiquity, when it was one of the main gemstones used. Now its value is fairly low, except for the rare green form called chrysoprase.