The Lost Arch Mine is one of California's great hidden bonanzas. Its popularity rivals that of the Lost Breyfogle or the Lost Pegleg. It is rumored to exist somewhere in the rugged Turtle Mountains of extreme southeastern California and is said to be the richest placer deposit of gold ever discovered in the mountains of the Mohave Desert.
The Turtle Mountains rise up from the desert floor some 25 miles west of Lake Havasu. The range is highly weathered and dissected. It is surrounded by a thick apron of alluvium which grades downward into the adjacent valley floors. The Turtle Mountains extend from the area just north of Mohawk Spring southwards for nearly 25 miles to Rice. The range is bounded on the west by Ward Valley and the salt beds of (dry) Danby Lake .
The Chemehuevi Valley bounds the Turtles on the northeast while Vidal Valley forms the southeastern boundary. To the south, the mountains descend into Rice Valley. A number of accounts exist of the Lost Arch Mine, some of them quite divergent. An early account concerns a small party of Mexican prospectors passing through the Turtle Mountains on their way to the goldfields at La Paz. Somewhere in the mountains they stumbled onto an incredibly rich placer deposit of gold. The Mexicans worked the placer long enough to construct an arch-shaped structure to live in and take out $30,000 worth of gold from the gravels!
Years later, a prospector named Amsden came across the same placer deposit while roaming the Turtle Mountains. Amsden barely made it out of that rugged country, but when he did his pockets were filled with gold. Till his dying day, he swore that the gold placer was located near a natural arch in the rocks. Other prospectors have scoured the Turtle Mountains in search of the legendary placer but none have found it. It remains one of California's most famous lost mines.
The Turtle Mountains contain no major mining districts or camps, although the southern end of the range is home to the Virginia May Mine. The nearest mining district is that of the Whipple Mountains, located 15 miles east of the Turtles. Gold was discovered on the western edge of the range by Argonauts heading for the Mother Lode country. A number of mines were developed in the area including the Dollar Bill, Independence, Baily, and Gold Standard. All are hosted in Precambrian