The wonders of the world

by John Loraine Abbott

Lead is one of the metals most anciently known, being mentioned in the books of Moses. It is found in some thirteen species of ore, only one of which (galena) occurs in masses sufficiently large to make it valuable as an object of mining and metallurgy. The uses of lead are so familiar that they need not be mentioned: they are known to all.

Among the most remarkable lead mines of the world, may be mentioned those of the state of Illinois, including also parts of Iowa and Wisconsin, which have been, and still are immensely productive, extending over thousands of acres, and furnishing the mineral in the richest abundance. These mines were formerly known as the mines of “Upper Louisiana.” They are now chiefly worked in the vicinity of Galena, a city which has sprung up, and is almost entirely supported by the trade in lead. So vast is the production of these mines, that forty million pounds of lead, valued at sixteen hundred thousand dollars, were shipped from Galena alone, in 1853. The mineral in one of the earliest opened mines, is said to be of two kinds, the gravel and fossil. The gravel mineral is found immediately under the soil, intermixed with gravel, in pieces of solid mineral weighing from one to fifty pounds. Beneath the gravel is a sand rock, which being broken, crumbles to a fine sand, and contains mineral nearly of the same quality as that of the gravel. But the mineral of the first quality is found in a bed of red clay, under the sand rock, in pieces of from ten to five hundred pounds’ weight, on the outside of which is a spar, or fossil, of a bright, glittering appearance, resembling spangles of gold and silver, as solid as the mineral itself, and of a greater specific gravity. This being taken off, the mineral is solid, unconnected with any other substance, of a broad grain, and what mineralogists call potters’ ore. In other mines, in the vicinity of the above, the lead is found in regular veins, from two to four feet in thickness, containing about fifty ounces of silver in a tun.

In Great Britain, there are numerous and exceedingly valuable lead mines, among which may be cited that of Arkingdale, in Yorkshire, and those with which Shropshire abounds. In the south of Lanarkshire, and in the vicinity of Wanlock-head, Scotland, are two celebrated lead mines, which yield annually above two thousand tuns of metal. The Susannah-vein lead-hills, have been worked for many years, and have been productive of great wealth. The above are considered as the richest lead mines of Europe.

Several of the Irish lead mines have yielded a considerable proportion of silver; and mention is made of one, in the county of Antrim, which afforded, in thirty pounds of lead, a pound of that metal. Another, less productive of silver, was found at Ballysadare, near the harbor of Sligo, in Connaught; and a third in the county of Tipperary, thirty miles from Limerick. The ores of this last were of two kinds, most usually of a reddish color, hard and glittering; the other, which was the richest in silver, resembled a blue marl. The works were destroyed in the Irish insurrections in the reign of Charles I. The mine, however, is still wrought on account of the lead it contains.

COAL MINES.

Coal is one of the most valuable of all mineral treasures, and one that is of the highest service in making the others available to the use and comfort of man. And hence it has been searched after with unremitting diligence, and worked with all the lights of science and the resources of art. It is found in beds or strata, in that group of the secondary rocks which includes the red sandstone and mountain limestone formations, commonly called the carboniferous group, or the coal measures. From the peculiarities of their position, they are often spoken of as coal-basins, and coal-fields.

There are two or three points of some theoretical interest and importance as to the origin of coal, on which geological authorities are nearly unanimous. One is, that our present coal is exclusively of vegetable origin, formed apparently from the destruction of vast forests and immense quantities of leaves and shrubs; another, that it was formed when the climate of the regions where it is found was not merely tropical, but ultra-tropical, instead of being as now, temperate; and a third, that its deposits, though originally regular, have evidently been since elevated, and often singularly dislocated and contorted by forces acting from below, and probably of a volcanic nature. Each of these points will more or less appear in the progress of the following remarks.

That the coal formations are of vegetable origin, is perfectly evident from even a slight examination, especially with the microscope. Let a piece of coal be cut in very thin slices, or plates, and its appearance will be like that seen in the following cut. The vegetable fossils thus shown are, indeed, very different from any existing species, unless it be a few which are the productions only of torrid climates. And while the cut gives the appearance of but a single leaf in each specimen, the masses of coal are generally more like one thick imbedded mass of leaves, not so much crushed together, as overlaying and mixed with each other. According to Dr. Linley, the coal vegetation consisted of ferns, in great abundance; of large coniferous trees, of a species resembling lycopodiacæ, but of most gigantic dimensions; of a numerous tribe apparently analogous to cactæ, but probably not identical with them; of palm, and other monocotyledones; and finally, of numerous vines, plants, &c., the exact nature of which is uncertain. Where leaves most abound, the coal is said to be of the best quality; though as any one kind of coal hardens, the impressions of such leaves become gradually less distinct, until finally they can hardly be traced, even with a powerful magnifier. A hundred and twenty varieties of these vegetable impressions have been found in the vicinity of Pottsville, in the course of a few months, each as distinctly marked as the most delicate tracings of an artist’s pencil; and in almost any coal formation, there are so many hundreds of different plants, trees, and flowers, that a single representative of each kind would form a vast museum. Specimens which exhibit impressions of the bark, limbs, or trunks of trees, are, of course, correspondingly large and heavy, and could not easily be sketched in a small engraving, while the variety of leaves and flowers is so great, that it would be tedious to mention and describe them.

THIN PLATES OF COAL.