The Boy With the U.S. Miners

by Francis Rolt-Wheeler

A hydraulic jet of high pressure, washing away a hill of gravel and sending the pay dirt through a sluice.

From "The Romance of Modern Mining," by A. Williams.

"That is why, Jim, even the richest-ored mine in the world—if it be uneven in its yield of gold per ton—may be worthless, and why a low-grade mine with an unchanging percentage may be worth millions, so long as there is plenty of it. It all depends on the cost of extracting the metal. There are scores, yes, hundreds of gold-deposits well known to-day, which cannot be worked as long as gold stays $20 an ounce, because it costs almost as much as that to get it out, but which would be big money-makers if the gold were worth $25. Three-quarters of the gold-mines of to-day would shut tight like a clam, if gold were to drop in price even a dollar or two. What a capitalist wants to-day is ore, and he is not interested in free gold. What a prospector looks for, is free gold, and he ignores the rock. I'm telling you all this, now, Jim, because it's what will be the important thing when we get to talking, later, over your find."

"That's all right," the old prospector answered, "but how can a man tell when he's tappin' a big lot o' rock or jest a little, if it ain't the free gold what shows him?"

"He can't tell, as a rule," the mine-owner rejoined. "It takes a geologist to do that. As I was saying, there are some rules to go by. Here, I'll give you a notion of how gold came to be in the rocks, and then you'll see what a geologist can tell and what he can't.

"To start with, you've got to begin 'way at the beginning of things, before the crust of the earth was solid and when all the rocks of the crust were in a melted and half-liquid state. So far as we can make out, the metals seems to have classified themselves at that time, more or less, according to density. The lighter elements came to the surface, the heavier ones stayed at the bottom. It wasn't merely a question of weight, but of gravitation, centrifugal action and a lot of things I won't stop to explain to you now. Gold, as you know, is heavy, that is, it possesses extreme density. It stayed therefore, mainly at the bottom of this semi-molten sea.

"But this sea, which covered the whole of the earth's surface, wasn't altogether liquid, as the oceans are to-day. It was a seething mass of different densities, some of it liquid, some of it slimy, some of it thick like sticky mud, acted upon by fearful whirlwinds of electric forces such as astronomers see in the sun to-day, and by powerful internal currents which created vast churning whirlpools of super-heated matter.

"It's impossible for us to tell where these electric whirlwinds passed or where these currents were. So, since the original separation of the metals was highly irregular, no geologist can say with certainty where gold or silver, lead or tin, will be found in the greatest quantity.

"Then there's another complication. As you know, most of the metals have chums or affinities with other substances, just as gold has with mercury. These chums of the metals were also in that molten ocean, but not always in the same proportions, nor yet distributed regularly. So metallic compounds were formed at different times and in diverse places. These compounds had varying densities, with the result that in later ages they behaved in a way quite different from the pure metal. You see, Jim, long before the crust of the earth was even formed, gold was scattered far and wide, and already was in different forms.

"Then, little by little, the crust began to form as the earth cooled. It was just a scum, at first, and was constantly broken up from below. As it got thicker, it resisted more and more, until the upheavals of the crust formed the mountains of the earliest or Primary Age. This crust, which was now solid rock, contained gold, but, naturally, nowhere in the same proportions. Some had much metal inclusion; some, little; some, none at all. Besides, between the mountains or in them, were vast volcanic craters, pouring up molten matter which became what are known as the eruptive rocks, and these, too, carried up gold from below. These rocks crystallized and the gold remained in them.