The Lost Cement Mine is a legendary gold vein situated in the eastern Sierra Nevada of California, United States.
It was supposedly found in 1857 by two men who were separated from their group while crossing the Sierras. They traveled through the "burnt country" and found the gold vein along the headwaters of the Owens River. Mark Twain searched for the Lost Cement Mine in the 1860s, and included his search in his book Roughing It. The entire story and later expeditions were published in the book The Lost Cement Mine by James W. A. Wright.