In the United States coal is the most valuable mineral product, pig iron is the next most valuable, and copper comes third with a yearly production of over a half million tons and a value of over $150,000,000.
Although in a general way copper is not nearly so vital to our mode of existence as iron is, since iron is the basis of our activities, yet copper allows variation in color and finish, and - through its extensive application in all electrical work - gives a breadth and convenience to many sides of our life which now would be discarded with much regret.
The mines and plants from one end of the country to the other are open to visitors, and the industry seems permeated with broad-minded and kindly-disposed men who do not fail to grace the literature, until it is a better reflection of the industry than is the case with any other technical subject of which the author knows.
The great hydrometallurgical copper mine of the world has been at Rio Tinto, Spain; that will still continue to be a great mine, but will be dwarfed by the tonnage and technique of the remarkable Chuquicamata mines of Chili which are now being brought to capacity by American enterprise.
Copper occurs in the following forms:
This is the mineral of the Lake Superior copper mines, and it occurs also in many other ore deposits.
The red oxide, Cu20, a mineral very high in copper, enriches many western deposits.
The black oxide, CuO, is a less important mineral but is found frequently in many mines.
The green carbonate, CuC03.Cu(OH)2, is a very conspicuous and important surface mineral.
The blue carbonate, 2CuC03.Cu(OH)2, often accompanies malachite.
The silicate, CuSiO3. 2H20; also is a surface mineral.
The copper pyrites, Cu2S.Fe2S3, form the universal and most important copper mineral.
The sulphide, CuS, is found as one of the main deposits of the Butte district.
The mineral, CU2S, is very common and important in many western mines.
These are complex minerals of note.
The basic sulphate, CuS04.3Cu(OH)2, is the mineral of the Chuquicamata mine.