Agate is an assortment of crypto-crystalline quartz; Silicon Dioxide. Black Agate gemstones a typical term for an unmistakably joined sinewy chalcedony. It is regularly found as layers lining Geodes. There are several names connected to the assortments of agate that are found all through the world. While a significant number of the names mirror the wellspring of the precious stone, different names are elucidating of their shading and example.