This begins a series of three geocaches on FS409.
There are two dikes that are part of the Rainbow No. 4 Claim. In 1940 about 1 ton of beryl, 5 tons of mica and 100 tons of feldspar was shipped from this site.
Feldspar is a common raw material used in glassmaking, ceramics, and to some extent as a filler and extender in paint, plastics, and rubber. Mica is a mineral that is commonly used in the electrical industry and was used to create window-like panes on stoves and lanterns. Beryl contains a very rare element called beryllium and the most common use is in the production of wire, although beryl has also been used on space shuttles.
Take FS409 off Highway 16 west of Custer. This is a seasonal gate that is closed to vehicle traffic December 15 to May 15. The gate is closed with a dummy lock during the summer and fall to keep the cows in. High clearance vehicles are recommended.