“The greatest thickness of any mass cut through at the Cliff Mine has been about three feet. Their occurrence through the vein is not regular. Barren spots alternate with productive portions. The same is the case in all the mines. The total product of the Cliff Mine for the year 1848 is estimated at 830 tons, averaging 60 per cent. During the present year more than half this amount has been already sent down, and there is enough more on the surface and in sight in the mine to warrant the belief that 1000 tons will be the product of the year’s work, or 600 tons of copper. The whole amount of copper annually imported into the United States is about the value of two million dollars, or about 5400 tons. But little has been supplied from our own mines. Nine such mines, then, as the Cliff, would render us independent of foreign supplies. From present appearances, after careful examination of the region, and consideration of the progress made in mining since my last visit in 1846, I feel myself warranted in expressing a decided conviction that this amount of copper must be supplied in very few years, and this metal soon become, as lead already has, one of export instead of import. The recent failures of mining speculations, wildly undertaken, and ignorantly and extravagantly conducted, may for a time check the development of these mines; but their wonderfully rich character is now beginning to be properly appreciated, as well as the reliance which may be put in the surface-appearance of the veins. Some curious features in their character and distribution have been detected, which have heretofore escaped observation for want of sufficient data, and which will, I believe, be found of great consequence in the selection of the best localities. These, after farther examination, I may at another time make public. The history of these mines, so far, has remarkably proved the foresight and excellent judgment of the lamented Dr. Houghton, particularly so in his predictions of the disastrous effects that must result from such speculations as have caused the country to be overrun by hordes of adventurers. “The silver found associated with the copper has not proved of much importance, perhaps for the reason that the greater part of it is purloined by the miners. The Cliff Mine has probably yielded more than thirty thousand dollars worth, of which not more than a tenth part has been secured by the proprietors. I saw myself, the present season, no less than six pounds and eight ounces of lumps and bars of silver seized in the hands of an absconding workman.”]