Imágenes de páginas

"It will also be remarked, that the designated lead region is almost exclusively confined to the northern half of the cliff limestone formation of Wisconsin, which por. tion is occupied by its middle and lower beds. The upper beds (lying in the southern portion of the district) do not, as already intimated, furnish productive veins of lead ore. The crevices in these upper strata seem to be less numerous, and either empty, or filled with iron ore (hydrated brown oxide), or calcareous spar (crystallized carbonate of lime), to the almost entire exclusion of veins of lead.

All the valuable deposits of lead ore, which have as yet been discovered, occur either in fissures or rents in the cliff rock, or else are found imbedded in the recent deposits which overlie these rocks. These fissures vary in thickness from a wafer to even fifty feet; and many of them extend to a very great, and at present unknown depth.

“Upon the whole, a review of the resources and capabilities of this lead region, taken in connection with its statistics (in so far as it was possible to collect these), induces me to say, with confidence, that ten thousand miners could find profitable employment within its confines.

“If we suppose each of these to raise daily one hundred and fifty pounds of ore, during six months of each year only, they would produce annually upwards of one hundred and fifty million pounds of lead more than is now furnished by the entire mines of Europe, those of Great Britain included.

“This estimate, founded (as those who have perused the foregoing pages will hardly deny) upon reasonable data, presents, in a striking point of view, the intrinsic value and commercial importance of the country upon which I am reporting - emphatically the lead region of Northern America.

“It is, so far as my reading or experience extend, decidedly the richest in the known world.


" The copper ore of Wisconsin forms an item in its mineral wealth, which would be considered of great importance, and would attract much attention, but for the superior richness and value of the lead, the great staple of the State.

"This ore occupies, in the district under examination, the same geological position as the lead ore; originating in the fissures of the cliff limestone. Discoveries of copper ore have, indeed, been made on a sloping hill-side near Mineral Point, within three or four feet of the surface; and was there found disseminated and imbedded in an ochreous earth. But, on following this deposit to the opposite side of the ravine (on section twenty-two, township five, range three east of the fourth principal meridian), the copper ore was traced into a crevice, and a regular vein has there been worked, to the depth of thirty or forty feet. The pieces of copper ore raised on this spot commonly weighed from a few ounces to ten or twelve pounds; and one mass thence procured was estimated at five hundred weight.

The course of this copper vein is from southeast to northwest; and if this line be continued either way, from the discoveries at Mineral Point, it will strike, almost exactly, the discoveries of copper ore northwest on Blue river, and southeast on the Peccatonica - a proof that the copper ore is not a superficial and vagrant deposit, but

1 This earth frequently contains particles, more or less numerous, of copper ore, which is then popularly termed “gozzin," and employed as a flux in the copper furnaces. The gozzin of Wisconsin yields, by analysis, from six to nine per cent. of pure copper - & large per centage for such ore.

exists in veins of uniform bearing; and that these veins are continuous, and, in all probability, extensive.

“The copper ore of this region compares very favorably with that of Cornwall. An analysis of a selected specimen of the best working ore of these mines, and of three average specimens of Wisconsin ore, showed that the latter contains from a fifteenth to a third more of copper than the former.

• The Wisconsin copper veins may rank among the most important that have yet been discovered in the limestone formation.

“Finally, the Wisconsin copper ore derives additional value in consequence of being found in the vicinity of, and often in the same mine as, productive veins of zinc ore.

The richest deposits of copper as yet discovered, are in the northern part of the State; a much fuller description of them will be found in the second part of this work, on Lake Superior.

It may be added, as an additional fact, whereby to estimate the value of the Wisconsin copper, that, in some of the European mines, “the ore does not contain above three per cent. of pure copper, and yet it pays for working ;" also, some of the Cornwall mines are worked profitably, at a depth of more than two thousand feet "from the grass, as the phrase there is. What a contrast these mines present to those of Wisconsin, many of which lie between fifty and one hundred feet from the surface. Here we have inexhaustible beds of the finest ore in the world, which have been proved, on analysis, to be superior to the English copper; besides, the miners say “they can afford to raise copper ore at the same price as lead, namely, from one and a half to two cents a pound;" but as it requires much more capital and skill than to smelt lead, they have hitherto been prevented. In the means of transportation we

[ocr errors]
[ocr errors]
[ocr errors]

are not surpassed by any in the world; a short distance of from five to ten miles will convey the ore to the shipping port. It is a burning disgrace to our country that so many thousand pounds of copper are yearly imported from England, and other parts of Europe, when we have such unlimited quantities at our own doors. There is copper enough in Wisconsin to supply the United States for years to come, and to spare. All that is wanting is capital and men to develop its rich resources.



"This ore, found in Wisconsin, usually occurs in the same fissures with the lead. It is chiefly the electric calamine—the carbonate of zinc of the mineralogist. Though a solid ore, it has an ochreous, earthy aspect, often resembling the cellular substance of the bone : hence it is familiarly known among the miners by the name of 'dry bones.'

“At some of the diggins' large quantities of this carbonate of zinc can be procured. Thousands of tons are now lying in various locations on the surface, rejected as worthless; indeed, as a nuisance. It is known to but a few of the miners as a zinc ore at all. An analysis of this ore proves it to be a true carbonate of zinc, containing forty-five per cent. of the pure metal.

“Sulphuret of zinc (sometimes called blende, and, by the English miner, 'black-jack') is also abundant in the Wisconsin mines. It contains from fifty-five to sixty-five per cent. of zinc, but is more difficult of reduction than the calamine.

“Sheet zinc is becoming an article of considerable demand in the market, for culinary purposes, and as a covering for valuable buildings, instead of lead. But the chief consumption of this metal is in making brass, well known to be a compound of copper and zinc.


[ocr errors]

“Large quantities, both of copper and zinc, are now imported from Europe into the United States, to supply the continually increasing demand for brass. It is not improbable that the district now under consideration might furnish of both metals a sufficient amount, at least for many years to come, to supply the entire United States with brass of home produce and manufacture.

“Of zinc, at least, there is assuredly a sufficient supply, not only for that purpose, but also for exportation. All the zinc now produced in Great Britain is trifling in quantity, and quite insufficient for the demand : so that a large quantity is imported annually into that island, chiefly from Germany and Belgium. The importation of zinc into England, in the year 1833, exceeded six millions and a half of pounds; a fact which may give us an idea of the importance of this metal as an article of commerce. Among the productive mineral resources of Wisconsin, the, at present despised, zinc ore may claim no contemptible rank.

[blocks in formation]

“ The iron ore of Wisconsin is of excellent quality, and in unlimited abundance. I explored, a few years since, in company with Professor Troost, Geologist of Tennessee, the iron mines of that State, which already furnish iron to a considerable portion of the Western States. And though I have seen no proof that iron exists in Wisconsin in deposits as extensive as in Tennessee, yet the locations of iron ore are numerous, and the quality of it, in general, is as good.

“In some of the townships, on the Wisconsin river, iron ore was found scattered in innumerable fragments over the entire surface, and of a quality so rich as to be crystallized in much perfection. The reports and specimens from that

« AnteriorContinuar »