Chalcedony

Chalcedony is the name given to the microcrystalline varieties of quartz the form concretionary deposits. They have been used since time immemorial both as gems, because of their color, hardness and ability to take a good polish and as precious materials for the production of ornaments or small sculptures.
Chalcedony occurs in many forms, colors, and shapes. Chalcedony, agates, jaspers, bloodstone, cornelian, onyx, and chrysoprase all make up the chalcedony gemstones. The colors of Chalcedony vary and can be pale blue, yellow, brown or gray with nearly wax like luster.