Connecticut western news., 1876-01-07
MASSES OF COPPER.
How Mass Copper Is Mined---The Difficult
 ties Attending the Work.

How Mass copper Is MAned---Tho Dtmcul-
 ties Attending tho Work.
 The largest continuous mass of copper which has been taken out of the mines of the Lake Superior region was proba- bly, that from the Minnesota in 1857, which is variously stated as weighing APO tons and 470 tons. Its length was about forty-five feet, it's breadth or height twenty-two feet, and its greatest thickness eight feet. All such masses are very irregular and ragged in their form and thickness, thinning out gradu- ally from foot to few inches, and struggling through the vein until they connect with other large masses. This was the character of mass found in the Phoenix mine, one of the oldeston the lake, which mass altogether weighed some six hundred tons. But this was really a series of masses more or less connected by strings of metal, yet no one large part of it weighed, singly, over two hundred tons. A similar series of masses, weighing about six hundred Some of the Phpnix masses were four or five feet thick of solid copper. The Cliff mine has yielded masses weighing
 
 fifty tons in one piece. One of forty tons was taken out this year, besides numerous blocks weighing from one to eight tons. This mine and the Central are now yielding mass copper in abun- dance.
 It is of course impossible to pick, or to drill. or to break out such huge mass es of solid metal, when they are found by drifting upon the course of the vein. The method is as follows: The miner picks out, or excavates, narrow passage or chamber upon one side of thesmass, laying it bare as far as possible over its whole surface. It is usually firmly held by it's close union with the vein stuff, or by it's irregular projections, above, be- low and at the end. If it then cannot be dislodged by levers, the excavation of chamber is commenced behind the mass, and this excavation is made large enough to receive from five to twenty or more kegs of powder. In one instance, in the Cliff mine, charge of twenty-one kegs of powder threw down two hun dred tons of copper. Bags of sand are used for tamping, and the drift is closed up by barricade of refuse and loose dirt. After such blast the drift is, of course, charged with foul air, and it can not be safely entered for hours after wards. If entered too soon, men lose all strength in their limbs, and fall down.
 The huge masses of copper dislodged in this way are too large to be handled and got to the surface. They have to be cut up. The copper cutters are called in, and the mass is marked off in squares or blocks of suitable size. Copper cutting is a distinct art, and requires considera- ble skill and experience. Ordinary min CTS, however skillful they may be, can not cut up copper without long training.
 The tools are simply narrow chisels and striking hammers. The chisels are shaped like the parting tools of turner's. They are made of fiat bars of half inch steel, about two inches wide and eigh- teen inches long. They are chamfered each way like cold chisel, to form the cutting edge. This edge is made little longer than the thickness of the bar. The cutter holds the chisel md two men strike it. A thin slice or chip of copper is in this way cut out in O narrow chan. nel across the mass of copper. The operation is repeated until the narrow cut, but little over half an inch wide, has been carried through the mass. The chips cut out in this way are long, nar- row strips of copper only about half as long as the groove from which they are taken, the metal being condensed and thickened by the force of the blow.
 This work is necessarily slow and te- dions, and it costs SIP per square foot by contract. At this price, the cutters make g. per day. -Scientifc American.