Washington has a great variety of mineral deposits, and mineral production and processing is one of the major industries of the state. Mineral deposits are distributed throughout the state, but more are concentrated in the Northeastern counties. Many of the deposits, as in other areas, are either to small, too inaccessible, or too low in grade to be mined commercially at the present time, but increased prices and improved mining and processing methods undoubtedly will make it feasible to mine more of these deposits in the future.
Most of the Okanoganís gold and silver was secreted in mountains. This required tunneling to get at the ore and concentrating mills to reduce the volume shipped to smelters. Most mills stair-stepped down hillsides so gravity could move materials through the process. The end result would be silver concentrates placed in bags for shipment to a smelter, which would produce marketable silver bars.
This cross-section shows the type of process concentrating mill the Arlington Mining Company may have been planning. ( Drawing courtesy of Wayne Moen, State Dept. of Natural Resources).
2. Crushing rolls or heavy stamps "rising and falling 60 times per minute with thunder and clatter," making the mill tremble, crushed ore-bearing rocks into smaller pieces, while larger pieces were recycled back to the crushing rolls or stamps, smaller pieces dropped through screens into a settling bin.
3. In the settling bin, filled with water, the rock pieces were mixed with chemicals causing silver to float to the surface.
4. Silver particles were scooped off the top of the settling bin and moved to amalgamation pan where they were mixed with further chemicals to remove impurities. The material then flowed into a settling tank.
5. In the leaching tanks, silver tended to sink while impurities tended to float to the surface.
6. Finally, the precipitation tanks were drained and the silver concentrates placed in a smelting furnance "not shown." From here the silver concentrate were placed in bags for shipment to smelters which would produce marketable silver bars.