danger of collapse. Most mines stayed above the water table, being no more than thirty feet deep, such as the Allatoona Mine in Bartow County. The deepest was the Loud Mine, in White County, at one hundred and thirty feet. Large stamp mills appeared in 1833, at the Columbia Mine in McDuffie County. These reduced the ore to fine sand for additional panning, or for separation via mercury amalgamation. Besides the Calhoun Mine, other major gold mines included the Sixes, Logan, Elrod, Battle Branch, Pigeon Roost, Turkey Hill, Free Jim, Holt, Loud, Cleveland, Gordon, Horshaw, Lumsden, and Richardson. Nevertheless, by the 1840s gold mining saw a sharp decline, as the gold began to "play out". Aftermath When news of the California Gold Rush reached Georgia, many miners moved west in search of more gold; the assayer of the Dahlonega Mint, M. F. Stephenson, tried to convince them to stay. He declared from the Dahlonega courthouse steps to a crowd of miners, "Why go to California? In that ridge lies more gold than man ever dreamt of. There's millions in it." Yet, despite the departure of many miners, the mines in the Georgia Gold Belt continued to produce gold for years. Hydraulic mining and blast mining renewed interest in the 1850s. There were some 500 mines in 37 different counties. The Civil War brought most operations to a halt, but a few operations continued after the war, and several mines were reworked in the 1930s, during the Great Depression. It is estimated that Georgia produced about 870,000 troy ounces (24,000 kg) of gold between 1828 and the mid-20th century, when commercial gold production ceased. Before they were expelled, the Cherokee gained enough gold-mining experience to participate in later gold rushes in California in 1849 and Colorado in 1859. Cherokee gold miners gave the name to the town of Cherokee, California, as well as to a number of other geographic features in that state's gold-mining region. Experienced gold miners from Georgia played key roles in the beginning of gold mining in Colorado. Georgia miners Lewis and Samuel Ralston, along with some displaced Georgia Cherokee, noticed placer gold near the present site of Denver, on their way to the Sierra Nevada gold fields in 1850. They returned east in 1857, having failed to strike it rich; they remembered the gold just east of the Rocky Mountains. William Greeneberry Russell led a party of