It belongs to the same rock class, felsic, as granite but is much less common. The Amargosa River, which flows through nearby Beatty, gets its name from the Spanish word for "bitter", amargo. In its course, the river takes up large amounts of salts, which give it a bitter taste. "Bullfrog" was the name Frank "Shorty" Harris and Ernest "Ed" Cross, the prospectors who started the Bullfrog gold rush, gave to their mine. As quoted by Robert D. McCracken in A History of Beatty, Nevada, Harris said during a 1930 interview for Westways magazine, "The rock was green, almost like turquoise, spotted with big chunks of yellow metal, and looked a lot like the back of a frog." The Bullfrog Mining District, the Bullfrog Hills, the town of Bullfrog, and other geographical entities in the region took their name from the Bullfrog Mine. "Bullfrog" became so popular that Giant Bullfrog, Bullfrog Merger, Bullfrog Apex, Bullfrog Annex, Bullfrog Gold Dollar, Bullfrog Mogul, and most of the district's other 200 or so mining companies included "Bullfrog" in their names. The name persisted and, decades later, was given to the short-lived Bullfrog County. Beatty is named after "Old Man" Montillus (Montillion) Murray Beatty, a Civil War veteran and miner who bought a ranch along the Amargosa River just north of what became the town of Beatty. In 1906, he sold the ranch to the Bullfrog Water, Power, and Light Company. "Shoshone" in "Montgomery Shoshone Mine" refers to the Western Shoshone people indigenous to the region. In about 1875, the Shoshone had six camps along the Amargosa River near Beatty. The total population of these camps was 29, and because game was scarce, they subsisted largely on seeds, bulbs and plants gathered throughout the region, including the Bullfrog Hills. Geology The Bullfrog Hills are at the western edge of the southwestern Nevada volcanic field. Extensionally faulted volcanic rocks, ranging in age from about 13.3 million years to about 7.6 million years, overlie the region's Paleozoic sedimentary rocks. The prevailing rocks, which contain the ore deposits, are a series of rhyolitic lava flows that built to a combined thickness of about above the more ancient rock. After the flows ceased, tectonic stresses fractured the area into many separate fault blocks. Most of these blocks tilt to the east, and the horizontal banding of individual flows shows clearly on their western scarps. Within the blocks, the