Types of Mining

Types of Mining

by Todd Underwood

Placer
Placer mining involves any type of mining where raw minerals are depostied in sand or gravel or on the surface and are picked up without having to drive, use dynamite or any other signifigant means. The word placer means "sand bank" in Spanish. Specific types of placer mining are panning, dredging, sluicing, using a Rocker, or just picking up what lies on the ground.

Hydraulic
Hydraulic mining involves high pressure water. The water is

Operating hydraulic mining elevator and impounding works at North Bloomfield Mine

sprayed at an area of rock and/or gravel and the water breaks the rock up, dislodging ore and placer deposits. The water/ore

Hydraulic mining in Alder Gulch. Madison County, Montana.

mixtue is then milled. This is a very destructive way to mine and has been outlawed in most areas.

Hardrock
Hardrock mining entails diging into solid rock to fine minerals usually in their ore form (the metal plus oxygen). To do this, miners used picks and shovels, rock drills, dynamite and more. Miners dug either shafts that went straight down to follow ore bodies and veins, or tunnels which went somewhat horizontal into rock faces. Shafts usually had some sort of headframe (pictured left) standing above them to support the hoists. Shafts and tunnels were often supported with large timbers to prevent cave-ins. Most shaft or tunnel mines would eventually flood as they hit the water table and water would have to be continually pumped out. Sometimes there was so much water they had to abandon the mines.

Open Pit
Open pit mines involve digging large open holes in the ground as opposed to a small shaft in hard rock mining. This method of mining is most often used with minerals like copper and molybdenum. Open pit mines are very large and devistate the surrounding landscape as can be seen in this picture of the Bingham Canyon Mine near Tooele, Utah. Mining operations of this scale were not done too often in the 19th century.

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