DRILLING IN A COPPER MINE.
The copper mines of Lake Superior are generally very profitable, where they pay at all, but investments in them should be made with great caution. Many copper companies have been organized, and the stock has been put upon the market and sold, when the mine had no existence except in the brain of its originator.
MALACHITE AND ITS USES.
A very valuable substance found in copper mines is that known as malachite. Specimens of it are found in the Lake Superior district, in Australia, and sometimes in England. The greatest quantities of it—in fact the only quantities of any importance in the whole world—are in the Ural Mountains, in Russia. In the mine of Tagilsk, a pretty town of twenty-five thousand inhabitants, situated in the Ural Mountains, there is a valuable copper mine which produces immense quantities of malachite.
Malachite is a protocarbonate of copper, and by analysis yields seventy-one per cent. of protoxide of copper. It is distinguished for its beautiful green color, variegated in many ways, its fine texture, and its ability to receive high polish. It is used for jewelry, and is converted into tables, vases, and many articles of great beauty.
In the mine of Tagilsk, about thirty years ago, an enormous mass of malachite was discovered, and several years were required to remove it. If it could have been taken out in its natural state, it would have been the greatest curiosity of the known world. The whole weight of this mass was estimated at seven hundred and twenty thousand pounds. Sir Roderick Murchison examined this mass before it was touched by the wedge or hammer, and his description is quite interesting. He says,—
“The copper ground that we have been describing having been excavated by shafts, an enormous mass of malachite was detected at the depth of two hundred and eighty feet. These strings of green copper ore occurring at intervals were followed downward, when, increasing with width and value, they were found to terminate at the base of the present mine in an immense irregularly shaped mass of solid malachite. When we examined this mass, much of the surrounding matrix had been removed, and it presented an appearance of having been cast in a depression of the stone. We are disposed to view it as having resulted from copper solutions emanating from all the porous, loose, surrounding mass, and which, trickling through it to the lowest cavity in the subjacent rock, have in a series of ages produced this wonderful subterranean incrustation.”