Cradle (mining)

A cradle, or rocker, was a mechanical contrivance used in placer mining in the 19th century. It consisted of a box on rockers and moved by hand, and was used by gold miners to process gold-bearing soil, washing out the dirt and leaving the gold behind in the box. It does indeed resemble a child's cradle.

It must be manipulated carefully, to prevent losing the gold. Although big, and difficult to move, the rocker can pick up double the gravel, and therefore more gold in one day than an ordinary gold mining pan.

The rocker, like the pan, is used extensively in small-scale placer work, in sampling, and for washing sluice concentrates and material cleaned by hand from bedrock in other placer operations. One to three cubic yards, bank measure, can be dug and washed in a rocker per man-shift, depending upon the distance the gravel or water has to be carried, the character of the gravel, and the size of the rocker.

Rockers are usually homemade and display a variety of designs. A favourite design consists essentially of a combination washing box and screen, a canvas or carpet apron under the screen, a short sluice with two or more riffles, and rockers under the sluice. The bottom of the washing box consists of sheet metal with holes about 1/2 inch in diameter punched in it, or a l/2-inch-mesh screen can be used. Dimensions shown are satisfactory but variations are possible. The bottom of the rocker should be made of a single wide, smooth board, which will greatly facilitate cleanups. The materials for building a rocker cost only a few dollars, depending mainly upon the source of lumber.

References

•  "Cradle". Collier's New Encyclopedia. 1921.