Note: This is a historical method for gold mining and is not recommended as it is not legal in most places.
Ground sluicing consists in treating gold-bearing gravel, dug out by pick and shovel, by washing it in trenches cut in bed rock. It is like hydraulicking, except that the water is not used under pressure, and at times wooden sluices are dispensed with entirely, the rough rock serving for riffles. The lighter material is carried away by the water, and the heavier dirt remaining behind is collected and worked by rockers. Ground sluicing is often adopted where there is not a sufficient amount of water for the constant use of a box sluice, and a head can only be gotten for a short period after heavy rains. A ground sluice is then used, if there is abundant fall and outlet for the tailings. It is a gutter worn by the water in its flow, the miner assisting the operation by loosening the earth with a pick. The pay dirt is washed in by the stream or conveyed thither by manual labor. If the bottom be a hard, uneven rock, its inequalities will suffice to arrest the gold; if not, a number of boulders, too heavy to be moved by the stream, are thrown carelessly, into the sluice. This process saves only the coarse gold nuggets.
Ground sluicing is the favorite way of working small bars and gulch diggings, where a hose is not at hand or the water supply is too low down to use one. More grade and dump room is needed for this than for shoveling in; also more water, and the dirt can be worked very much faster. Bring the water across the ground as for shoveling in, and at the lower end dig a trench on a grade of one or one and a half inches to the foot, until the head of it is two or three feet deep; set a twelve inch or larger sluice box in and stop up the leaks, filling the trench with sod and rook around the head of the box. Now turn on the water, and with a pick help it to tear up the earth, throwing the large rock out of the way when you come to them, sending the mud, sand and gravel through the box. If the bed rock pitches to either side, it is well to work off the higher part first, as that is hard to reach, after the lower part is stripped. To clean up, the water is diverted from the channel and the auriferous matter collected, to be panned out or cradled.
Booming Out:
Booming; is ground
sluicing on a large scale, by means of an intermittent supply of water. The
water is collected behind a dam with an automatic gate, which, when the dam
is full, opens, and the entire contents of the reservoir go down with a rush
carrying into the sluices all the material collected below. The rush of
waters carries off boulders and dirt, leaving '.he heavier particles of gold
and magnetic iron, or black sand, collected behind on the bed rock floor. Booming is a very old
English style of mining, and is used to advantage in cleaning out steep,
narrow gulches, where labor is expensive and the surface dirt deep. It is
accomplished by setting up a string of large, strong sluice boxes in the
lower part of the gulch, anchoring them firmly to the rock, and building a
reservoir in the upper part, sometimes as much as half a mile distant. A
large gate is put in, that will let out as much water as the boxes will
carry off, usually being made automatic, so that it will open When the
reservoir is full, letting out a flood of water that takes everything with
it while it lasts, and gives the operator |a chance to build walls and shape
its course between floods, thus doing away with picking and piping except in
cleaning up. They are also called self shooters. As the gate might puzzle
you to build, here are the directions: Build a dam of sticks, stones and
dirt, placing in the bottom of it a covered box one-half the size of your
sluice boxes- place a gate in the head of it, to be opened by lifting. Place
an overflow box on top of the dam, extending over the outside; place a lever
there also, hanging the gate on one end of it, and a weight box on the
other, in such a manner that it will pull the gate open when full.
Cleaning Up.
When for any reason it is
desirable to clean up, strip all gravel and loose dirt off the bed-rock,
washing it down towards the boxes. When that is finished turn off the water
flow, sending it around some other direction. When the bedrock is dry take a
pick and dig out all the seams and crevices and scrape them clean; shoveling
the dirt always down toward the box, starting from the highest part. When
the pile of dirt gets too big to handle, turn on the water and wash it
through, putting in the last pile at the head of the box very slowly, to
keep from clogging the riffles. When all the gold from the
race above has been washed down and is in the box, turn off all but a very
little water, leaving enough to cover the bottom of the box about one fourth
of an inch deep, and take up the riffle at the head of the box, washing the
mud and sand down very slowly and throwing out the gravel, taking up the
last of it with a small scoop and panning it. But do not take up the last
riffle while there is running water in the box, unless you have a cleat over
an inch high in the tail of the box to catch the gold.
Continue on to:
Placer Prospecting: Part I
Placer Prospecting: Part II
Placer Prospecting: Part III
Placer Prospecting: Part IV
Placer Prospecting: Part V
Placer Prospecting: Part VI
Return To:
All About Placer Gold
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