Nearly every miner is more or less tied to his own theory as to where gold is likely to be found, which is the result of his own observation and study, and, when he finds out, and is compelled to acknowledge to himself that his own pet theory is wrong, he usually contents himself with that proverb of the ancients that “Gold is where you find it," yet it remains a fact, that you are more likely to find it among some kinds of rock than among others, and it may be set down as a rule that, when all the rocks you can find in a certain region lie in horizontal layers, whether they are of slate, limestone, sandstone or lava, and the boulders in the streams consists of the same material, it is not worthwhile to look for gold in that region. If the hills are rounded at the top like haycocks, round boulders of porphyry and pieces of quartz are common in the streams, the stratified rocks dip under the hills, and dykes of porphyry and father eruptive rock are common, then gold is likely to be found not far away. In many areas, the largest and best mines are usually found near where the longest and strongest traces of intrusive rock cross that part of the country rock which carries the gold. And, sometimes it is the eruptive itself which furnishes all the gold, though its step mother, the quartz, gets the honor. Among old time miners it is said that "quartz is the mother of gold," and, as a matter of fact, when both are found in the same kind of country rock on one hill, they are nearly always both in the same fissure, or vein; though either one may be found with scarcely a trace of the other. Veins containing gold, however, nearly always contain either quartz, iron or talc also, and often all of them, and many other metals, making a rock that almost anyone would recognize as ore, and with a little practice could readily trace it home, if not too much scattered.
Among placer miners black sand is said to be an indication of gold. As a matter of fact, when both gold and black sand are in the bed of the same stream, where the current throw one they will throw the other also, as both are much heavier than common sand. So, in prospecting a stream, if you get one in large quantities and none of the other, you can take it for granted the other is not there.
Methods and Appliances:
Panning, heretofore described, is used in prospecting, in cleaning up and in
mining, where only a small amount of dirt is to be handled, and the
facilities are not at hand for doing it any other way. Dry washing,
practical only in very dry climates, is accomplished with machines of
various sorts, which it would take a book larger than this to describe. Most
of them utilize the principles of a bellows blower, or fanning mill, and
screen the dirt to different sizes, and blow it away, keeping the gold. The
rocker comes next to the pan in size and capacity, and is very useful in
mining on a small scale. To build a rocker of the ordinary size takes about
feet of timber. However they may be built of any size desired, depending to
circumstances and material at hand. For the ordinary take a clear board 12
inches wide and about 30 inches long for the bottom. For the sides take two
boards, 12 inches \Aide at 12 inches from one end and tapered to 11 inches
at the short end, and three inches at the other, and the same length at the
bottom. For the higher end a board 12 inches wide, 1 inch thick, 16 inches
long at the top 14 at the bottom, will make it the right shape. At the lower
end put on a cleat not over 11-2 inches high. By nailing these together in
the right manner you make a scoop-shaped box, 11 inches deep at one point
and two inches at the farther end, 12 inches wide at the bottom and 14 at
the top. Now take four boards about 4 inches wide and scant 12 inches long,
nail box fashion 12 by 14 inches, and cover the bottom with a perforated
screen, made by punching one quarter inch holes in a piece of sheet iron.
Now put cleats in the high end of your box, about 2 inches from the top, for
the screen to rest on, and put another across the top to brace it. Next make
the apron by tacking a piece of canvas on a frame that is made to fit inside
the box on an angle, so that it will catch the sand and mud that comes
through the screen and carry it to the back end of the box. The side bars of
the frame should project about 2 inches beyond the canvas at the lower end,
so that it will not choke up with sand. Now put cleats in the high end of
your box, about 2 inches from the top, for the screen to rest on, and put
another across the top to brace it. Next make the apron by tacking a piece
of canvas on a frame that is made to fit inside the box on an angle, so that
it will catch the sand and mud that comes through the screen and carry it to
the back end of the box. The side bars of the frame should project about two
inches beyond the canvas at the lower end, so that it will not choke up with
sand. Now put rockers under the box, about six inches from each end and
about three inches high, and put a pin in the center of each to keep it from
sliding about on the foundation when tilted from side to side. Put a handle
on the top of the box to shake it with, and if you are going to mine fine
gold, spread a piece of cloth on the bottom and fasten it down with cleats.
Set it on a smooth foundation so that the open end is about three inches
lower than the other, and you are ready for work. Now put a shovelful of
dirt in the screen and pour water on it with a dipper, shaking it meanwhile.
When the mud is all washed through throw out the gravel, but save the big gold nuggets; also take out your apron once in a while and save the contents for panning. Rocking is the most practical method where the necessary amount of swift running water cannot be had. The self-dumping rocker will handle the dirt much faster than when two men are working together. To build the simplest of the self-dumping rockers take two boxes 3 or 4 feet long and a screen long enough to cover the bottom of one of them. The boxes should be 12 inches wide and 6 inches deep, with the end closed, and mounted in a frame on rockers, so that the sand and mud from the upper box will drop into the head of the lower, while the gravel will be carried on and dumped on the ground. The boxes, being given a grade or slant of about 1.5 inches to the foot, should be set foot or so apart at the front end, where the dirt and water is put on, and the mud runs out.
The screen should be mounted in the upper box, an inch from the bottom, and extending 2 inches beyond, so as to waste the gravel, water being poured on with a big dipper, as needed, to wash the mud and gold through the holes. Shallow riffles may be put in if needed, and a blanket should be plated in the lower box to catch the fine gold, being fastened down with cleats, or other means, as your ingenuity suggests. Such a rocker may, under favorable conditions, be made to handle four or five yards per day of dirt.
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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