ORES OF THE BITUMINOUS COAL MEASURES.
The principal bed of the bituminous fields is that which we have mentioned as existing above B, or in connection with the buhrstone or ferriferous limestone. This bed seems to be coextensive with the measures in which it exists, which spreads over the greater portion of the vast Alleghany coal-field, and, perhaps, may be found as extensive as the horizon of coal-bed B, or the limestone which it accompanies.
Its thickness varies from one to four feet, and its yield of metallic iron is from 25 to 50 per cent. If each square yard of this seam is capable of producing one ton of iron —which is a low estimate—throughout one-half the area of the Alleghany coal-field, the total amount on comparison would sink into insignificance the celebrated iron mountain of Missouri and cover out of sight the great iron regions of the lakes.
But this ore, when mined beyond the influences of the atmosphere, will not produce good iron without an admixture with the brown hematites of the limestones or the ores of the gneissic belt, and these, as we have shown, are always available to our great manufacturing centres. A combination of the magnetics and specular ores, which are "cold-short," with these calcareous ores, which are "red-short," produces a good iron for all ordinary purposes; while an admixture of hematites with the calcareous ores answers the same purpose.
There are two prominent seams of iron ore found in the lower coal measures of the Alleghany field. The second lies some distance above the buhrstone ore, and in the vicinity of the Freeport, or Curlew, limestone. The exact locality of this ore we cannot fix, but believe it to be on the same horizon with the ores in the vicinity of the Mammoth bed of the anthracite regions. But this ore is less reliable than the first, and is not so persistent in its spread. On the Great Kanawha it is found in workable dimensions, and its outcrops may be found at intervals throughout this great field; but it is seldom developed in a condition to attract attention.* The accompanying figure, 175, illustrates the position of the calcareous or buhrstone ore, and its connection with the accompanying limestone and coal.
There are many theories—and some of them very elaborate—advanced to account for the formation of peculiar ore-beds. But we do not see any reason to speculate beyond the common and natural processes, which we can readily comprehend, to account for the formation of the sedimentary beds of our coal-fields.
We find them generally deposited on beds of coal, lime stone, or shale ; and we can no more wonder that a bed of ore should be stratified over thousands of square miles, than that so many beds of sandstone are de posited in uniform strata throughout the Appalachian basin. The ore is more dense than the sandstones and slates with which it is found, and is the first to be pre-. cipitated from every great volcanic eruption. We find, however, the presence of lime important to the chemical separation or segregation of the iron from its accompany ing earthy matrix ; and, though not invariably, we gene rally find the ores purer and in greater quantities in the vicinity of limestone than when beyond its influence.
The character of the ore is due to other causes; and when we find the carbonate of iron in the coal measures and in connection with its coal-beds, we are not surprised that it is not peroxide, sesquioxide, or magnetic oxide, but consider it the natural consequence of its contact with the carbon which then existed in profusion throughout the coal measures and the waters in which they were deposited.
We shall not attempt to trace or describe the uncertain ore-beds in the upper coal series. The extent of the coal measures lying above the Mahoning sandstone is limited, and the ore-beds which they contain are of small dimensions and uncertain character.
We know but little more than that several such beds exist in the upper measures.
With this brief notice of the ores of the great Appalachian formations we must close this chapter; but we cannot dismiss the subject without a few words in relation to the magnitude of our iron deposits, their great variety, boundless extent, and availability.
Magnificent as our coal-fields are, they do not surpass our resources in iron; for both are on a scale of magnitude corresponding with the vastness of the country in which they exist and the population which it is destined to support.
A bountiful Providence has stored our mountains with unlimited supplies of the most valuable of minerals. The valleys and plains teem with productiveness, the land is rich in corn and wine, and the bowels of the earth fat with oil. We may invite the poor and oppressed of the world to come and partake; but we must protect ourselves against the monopolists and oppressors of the Old World, if we would profit by the abundance of the New.