Location
The Railroad Creek mining district, named for its most prominent stream, occupies about 97 square miles in northwestern Chelan County. It indudes all of the area drained by streams emptying into the west side of Lake Chelan north of Bear Creek exclusive of the Stehekin River drainage. It is separated from the Stehekin mining district to the north by prominent ridges, and it is bounded on the west and southwest by the Cascade Range and Chelan Mountains. A ridge north of Bear Creek forms the southern boundary, and Lake Chelan the eastern boundary. The area is extremely rugged, and the only road serving it is a short private road connecting the Holden mine on Railroad Creek with Lucerne at Lake Chelan. Both Lucerne and Stehekin at the end of the lake receive freight and passengers by scheduled boats from Chelan.
Geologic Section
The whole of the district with the exception of a small area southwest of Bonanza Peak is represented on the preliminary geologic map of Washington (1936) as being in Mesozoic intrusive rock. However, it is known that there are present also younger diorite and older metamorphosed sedimentary and igneous rocks now gneisses. A small area southwest of Bonanza Peak is covered by andesite.
Ores and Ore Minerals
The ores of this district are of copper, gold, silver, lead, zinc, and molybdenum. The ore minerals are chalcopyrite, pyrite, pyrrhotite, sphalerite, galena, pyrargyrite, and molybdenite.
Ore Deposits
The copper-gold-silver ores are typified by the ore of the Holden deposit, where the sulphides, in some places accompanied by quartz, occur disseminated in biotite schist and quartzite in a large xenolith or roof pendant in diorite. Ore minerals are found in small quantities in the diorite also. Some large solid masses of sulphides are to be found, but in general the ore minerals are present as small scattered grains. The molybdenum deposits are well-defined quartz veins cutting granitic rocks. The molybdenite occurs across the whole width of the veins but is concentrated near the edges. There has been little or no alteration of the host rocks at their contact with the veins.
Timber and Water
The district is well timbered and precipitation is heavy, thus timber and water are easily obtainable for mining and milling purposes.
