“Agate” is defined by the American Geological Institute Glossary (1960) “as a kind of silica consisting mainly of chalcedony in variegated bands or other patterns commonly occupying vugs in volcanic and some other rocks.” Dana’s Textbook of Mineralogy (1898) defines agate as “a variegated chalcedony. The colors are either (a) banded; or (b) irregularly clouded; or (c) due to visible impurities as in moss agate, which has brown moss-like or dendritic forms, as of manganese oxide, distributed through the mass. The bands are delicate parallel lines, of white, pale, and dark brown, bluish, and other shades; they are sometimes straight, more often waving, or zigzag, and occasionally concentric circular.