Gold quarters, halves, and dollars were also privately struck in California during the gold rush to relieve the chronic shortage of “small change” that resulted from the relative isolation of the West. Various private mints turned out these diminutive coins from 1852 until 1882, when the U.S. government passed a law forbidding all private coinage. Both round well as South, virtually disappeared during the war years. Fractional paper notes (shinplasters) and postage stamps had to substitute for small change. The Carson City and Denver Mints. In 1870, a branch mint was opened at Carson City, Nevada, to facilitate the coinage of the great new silver and gold deposits of Nevada and the Central West. The Carson City mint remained in operation until 1893, and provided numismatists with the rarest and generally the most valued mint mark on U.S. coins. In 1906, coinage functions in the West were renewed by the opening of a new branch mint in Denver, Colorado. The Four-Dollar Gold “Stella.” The most unusual and certainly one of the rarest of the gold—coin types of the U.S. was the $4 Stella of 1879 and 1880. There may be some question whether these coins can be regarded as a legitimate issue, as they were only minted as trial pieces and existed solely in proof condition. They were never minted for circulation. But collectors have apparently no doubt about their numismatic value; the going rate for Stellas starts at $6,000 and goes to $17,000.