Moss agate is a translucent chalcedony with green moss-like inclusions, usually hornblende. When the hornblende oxidizes, the color of the moss agate can be brownish or reddish. Moss agate is often cut in smooth slabs or flat cabochons in order to feature the moss-like images. Moss agate is often confused with dendritic agate which features tree-like or fern-like inclusions of iron or manganese. These resemble ice crystals on windows in winter and are usually black or dark brown.