Breccia (Italian), a compound rock composed of angular fragments, which appear to have once existed in other formations. If the fragments, before being reunited, have been rolled into the forms of pebbles, the new rock is called conglomerate or puddingstone. These and breccias are of frequent occurrence among the stratified rocks. The Potomac marble, of which fine specimens are seen in the capitol at Washington, is a breccia of marble, sandstone, and other minerals found in the new red sandstone formation, where it crosses the Potomac. Its various components having different degrees of hardness, it is a difficult rock to polish, which prevents its coming into general use, as its beauty would render desirable. When breccias are produced from rocks originally stratified in their layers, it is curious to observe how the lines of these layers are preserved in the broken fragments, and may be traced in the various directions in which they are thrown together. Breccias are also prepared artificially. (See Conceete).