Hart was a short-lived gold mining town located in the Mojave desert, in San Bernardino County, California. It existed between 1908 and 191…Hart was a short-lived gold mining town located in the Mojave desert, in San Bernardino County, California. It existed between 1908 and 1915, and was located on the northeastern edge of Lanfair Valley near the New York Mountains. The area is now in the Castle Mountains National Monument, administered by the National Park Service.