Dendritic Agate is a variety of Chalcedony, a mineral in the quartz family, with inclusions of iron or manganese that look like plant or tree life. This iron and manganese is known as dendrite, which is Greek for tree-like. Dendritic Agate is not technically considered an agate, due to the fact that it does not have much banding in the stone, but it is still classified in that group. This form of Agate appears in white, gray, colorless, blue, and yellow while the dendrite is black or brown.