|Montana Historical Society Photograph Archives, Lot 26 B7 F6|
Wednesday, January 15, 2014
Placer gold is that which is loose in the soil and closest to the surface. Placer mining requires water to wash the dirt, perseverance, and a strong back. Gold is the heaviest material in the soil, and so in the process of washing, the heavy gold is the residue remaining in the pan or the sluice box. The rich goldfields that drew miners to Montana in the mid-1860s only held so much placer gold. Miners wanted to be sure to extract all of it, and so when that closest to the surface was depleted, they resorted to other methods of extraction. Hydraulic mining, or power washing, was one method. The Romans used a similar technique. They filled a reservoir or tank above the area to be flushed and allowed the water to flow down the hillside to expose the veins of gold. The first hydraulic mining in the West was done in California in 1853. Using a hose made of rawhide and a wooden nozzle to channel the water into elevated flumes, gravity created enough water pressure to move large rocks and boulders. Miners employed much the same method at Bannack, Alder Gulch, and Last Chance. They created a reservoir, and then water wheels channeled water under tremendous pressure into huge hoses. These were then directed to the hillsides to power wash the soil down to the bedrock. A series of sluices filtered the dirt. This destructive mining method drastically changed the landscape, reducing once-timbered hills to bare rock.