View of hydraulic gold placer mining in Mesa County, Colorado; shows jets of water, hills, and Uncompahgre Creek.
Date
[between 1880 and 1900?]
Notes
Condition: soiled spots.; Printed on back of stereo card: "The simple pan, used by the first gold diggers, gave way soon to the cradle, and this, in turn was replaced by the socalled placer mining in which powerful streams of water are directed upon the auriferous masses of rock, clay and sand. In order to provide the necessary water and pressure mighty dams had to be erected to convert the gorges between the mountain ranges into reservoirs, and tunnels, canals, and pipes are employed to bring the water to the points of work. The water spouts generally with a pressure of five atmospheres, sufficient to wash away the gravel and smaller rocks, leaving the larger lumps of rock to be removed in some other way. The clay and sand are washed into long, deep ditches, where the gold is separated from the coarser material which is then removed and dumped into canons and crevices. This system is by no means perfect, as twelve million parts of gravel must be worked to gain one part of gold, and from 20 to 50 per cent of gold is lost in the operation, even when mercury is used. The refuse contains large quantities of gold in small particles, and is sometimes assiduously worked over by Chinese and others."; Title printed on front of stereo card; at head of title: "1240."; R7100601920
