VIRGINIA COPPER MINES. The copper mine of the Manasses Company is located in Fauquier county, Virginia. From the report of Professor A. S. Piggot, of Baltimore, we have made such extracts as will serve to inform our readers of the nature and location of the vein: The general direction of the mountain range is northeast and southwest, running parallel with the Shenandoah mountains, which divide the valley, and cut off from it the vale of the Shenandoah river, and with the great eastern range of this continent, the Alleghanies. Spurs of considerable height shoot out at various angles from the eastern side of this range, inclosing valleys and subsiding into the hills which rise from the tertiary formations. These mountains are a primitive formation, and consist chiefly of stratified rocks, which have been thrown up and displaced by volcanic force acting from below. The principal components are clay slate, which is most superficial; graywacke slate, gneiss, and occasionally some stratified sienite, chlorite, and talcose slates. These are all more or less tinged with epidote, chloride of iron. The strata are generally very regular, except where they have been dislocated by veins of minerals running through them. They have an inclination of about 45 degrees to the southeast. The slopes of the mountains are every where covered with loose fragments, which have come from the disintegrations of the rocks composing them. Some of the scattered stones are flat, and have come from the mass of the mountain; while others are large, irregular boulders, composed of the same materials, with the veins, hereafter to be described, and, like them, containing copper. It was, in fact, the discovery of the metal in one or two of these boulders which led to the explorations that have since been made. The veins actually traced up to this time are three in number. The courses of two of these intersect one another, close to the boundary line between Mr. Hall's and Dr. Taliaferro's farms, at the summit of one of the mountains rising from the gap, about eight hundred feet above the level of the railroad. The ascent, however, is so gradual, that there is a good wagon-road passing close to the line. The first of these veins has been opened in several places, and traced for a considerable distance along the mountain. It is a true vein, with welldefined walls. It has been opened to the depth of only six feet on Mr. Hall's property, and of nineteen on Dr. Taliaferro's, and yet a large number of very rich specimens have been taken out. The other vein has not yet been opened upon Mr. Hall's farm; but from the regularity of its course, as shown by the openings made on Dr. Taliaferro's property, one of which is within a few feet of the boundary line, it is absolutely certain that it must continue through Mr. Hall's lands also, in the same direction. These veins form an acute angle with each other, and their direction is nearly that of the axis of the ridge. The third vein is lower down the mountain, near the gap. It runs very much in the same direction with the other two, cutting the strata, nearly in the course of the mountain range, northeast and southwest. The veinstone in all these seems to be granite or sienite, altered by the action of fire. This constitutes the basis. They contain large quantities of epidote and chlorite, and are full of masses of quartz and scattered bits of feldspar. The lower vein contains also asbestos, fibrous talc, and titaniferous iron. Chlorite, epidote and quartz, are found in crystals here, and so, I am informed, though I have not seen them, are the various ores of copper. The importance of this fact, as an indication of the value of these mineral veins, I need not point out. The copper is every where disseminated through the upper veins as black and red oxide, carbonate, silicate, and native copper. In the lower vein, which is on the level of the railroad, and cut by it, pyrites is the only ore, with the exception of an occasional speck of carbonate, that I could find. This vein has been followed for a mile or more along its outcrops. As pyrites usually lie deep, the probabilities are, that this vein will prove valuable when it is worked, especially since the metal is every where so abundant in the surrounding moun tains. It is manifest, therefore, that there is copper in great quantity and of much value on this estate. The resemblance between these veins and those of the Ural, which have yielded from four to nine millions kilogrammes of eighteen per cent. ore a year, is very striking. The only question to be asked, is-Can they be worked to advantage? This is at once answered by a consideration of the character of the veinstone, the position of the land, and the facilities of transportation. As for the first, I would say that I have been in the cuts made for exploration, and had no difficulty whatever in procuring specimens, though I had but a little hammer with me. I have understood, also, from those engaged in blasting it, that it is not very hard to drill. The situation of the land is admirable. The facilities for drainage are great, and there is excellent water power upon the farm. As for transportation, I have already said that the railroad runs directly through the property, which is only about seventy miles from Alexandria. An inclined plane could be constructed with very little difficulty, which could carry the ore from the mouth of the mine to the railroad. PROFESSOR PIGGOTT'S ANALYSIS OF ORE. No. I. is a piece of veinstone, in which the unaided eye can detect no copper. Its general hue is a greenish gray, with a sort of blush of pale reddish brown. This is shown by the lens to be produced by minute specks of native copper scattered through the mass. The poorest portion of it was selected for analysis, and the rich bits carefully broken off. Its powder was something between a sorrel and a fawn color. It yielded 27 per cent. of copper. No. II. is a piece of veinstone containing ore. The prevailing color of the stone is green, from the infusion of epidote throughout the mass. The ore appears in the form of shots and streaks of black oxide, with occasionally a small fibre of native copper. The powder was a reddish brown. This yields 18 per cent. of copper. No. III. is a piece which could hardly be distinguished from the last by the unaided eye. If any thing, it looked less promising than No. II. The powder was the same color. Its percentage of copper was 27.7. No. IV. is a bit of pyrites from the veins on the railroad. It was knocked off from a large fragment of rock blown off the roof of the vein during railroad excavations. This contained a large quantity of feldspar in beautiful rhombs. When freed as completely as possible from veinstone, it yielded 14.1 per cent. of copper. No. V. is another piece of pyrites, containing about as much rock as ordinary dressed ore. It gives 8.8 per cent. No. VI. is a piece of quite pure ore, knocked off from one of the pieces taken from the vein opened at the summit of the hill. It is a mass of black and red oxide, inclosing native copper. It yields 89.1 per cent. of copper. MARYLAND COPPER MINE. The Dolly Hyde copper mine, of which we have a report of some length by Dr. Charles T. Jackson, is located in the town of Liberty, in Maryland. The description of the vien is thus made: "The present openings of the Dolly Hyde mine show that the copper ore is contained in a large vein of white, fine-grained dolomite, or magnesian limestone, which bears evident proofs of having been once in a fused condition. This limestone is filled with segregated masses, and string-veins of rich copper and silver lead ores. The limestone vein is about 110 feet wide, and is included between strata of blue, green, and violet-colored clay slate rocks. The ore, dressed coarsely for the furnace, has yielded about twenty-five per cent. of copper. It may be raised, by the use of proper machinery, to forty per cent. copper ore without much trouble. VOL. I.-12 THE COPPER TRADE OF GREAT BRITAIN. The following details respecting the copper trade of Great Britain will be found to be of interest by all who are engaged in mining or smelting copper in this country: The annual average sales of copper ore in Cornwall and Swansea together, during the last seventeen years, have been 203,848 tons of 20 cwts. each, or 194,141 of 21 cwts. to the ton (by which it is sold), and the average annual value £1,419,285. The average yearly manufacture of copper in Swansea, &c., during the last seventeen years, has been 18,714 tons.-Braithwaite Poole's Statistics of Commerce. In Great Britain there are 176 copper mines now working, and the ore therefrom is smelted at the furnaces and works, chiefly in Swansea, Amlwch, Bagillt, Liverpool, St. Helens, and Cheadle. In Cornwall, owing to the want of coal, the British ore is not smelted there, but mostly sent to Swansea, it being cheaper to carry the ore to the coal, than the coal to the ore-the lesser quantity to the greater. The countries from which foreign ore is chiefly imported into England are Cuba, Australia, and Chili, and the ports to which it is sent are Swansea, London, and Liverpool. The total weight of copper manufactured is not large, although the value is considerable; and it requires a large capital to carry on the business, which, in this kingdom, is entirely in the hands of about a dozen rich companies, and the trade is managed very respectably. A curious custom of selling ore has long existed. Meetings called "ticketings" are held periodically-generally every week on a Thursday in Cornwall, at Redruth, Truro, Camborne and Poole; commonly every fortnight on a Tuesday, at Swansea; also occasionally in London and Liverpool-when each individual is presented with a printed ticket, or account of the various lots of ore offered for sale, having blank columns ruled, wherein he inserts the price at which he is willing to become the purchaser of any lot, and the highest figure of course commands the purchase; but in the event of any two or more parties writing down the same figures for any particular lot, the ore is divided between them. The chairman of the meeting being the largest vendor, takes each list from the bidder, and draws a line under the highest sum offered, when he is said to "tick it," thus may the derivation of the term "ticketing" be accounted for. Copper ore is always assayed before being purchased, each buyer and each seller having his own assayer; and the sales are effected from their reports; but, if any difference should arise, a third assayer is called in, whose decision is final. The principal importers of foreign copper ore into Liverpool are half a dozen leading merchants; and the British ore is chiefly consigned to the agents of the copper merchants, of whom there are about a dozen in Liverpool. The vessels generally discharge their cargoes at the Harrington dock, where there is an open yard or depot, and a stock of 500 to 1500 tons of ore; also a mill for crushing it, as the ore is now always crushed before being sampled or smelted. The yield of copper varies according to the quality of the ore from fifteen to seventy-five per cent., and the price fluctuates fifty per cent. An average yield of British ore may be taken at seven per cent., and that of foreign ore at seventeen per cent. The quantities of copper ore of all sorts imported into Liverpool, foreign and coastwise (always in bulk), last year, are recorded as follows: The total quantity of British manufactured copper-in cakes, ingots, bolts, &c., and sheets packed in cases-imported into Liverpool last year, principally from Swansea, Llanelly, and Bagillt, was, 7,078 tons, and the metal sheathing brought by railway and inland navigation amounted to nearly the same weight. The exports of manufactured copper are chiefly made from London, Liverpool, and Swansea, to the United States of America, to France, the Mediterranean, and East Indies, where the sheets are frequently used in lieu of slates for roofing. Our exports from Liverpool last year were as follows, only fortytwo tons of which was foreign copper re-exported : To the United States, To France, Mediterranean, &c., To the East Indies, Total, 66 3,550 tons. 5,625 tons. Formerly the East Indies was our best market, but latterly the trade thence has fallen off considerably. The entire value of the copper trade of Liverpool last year, including metal sheathing, approached £1,500,000. THE CONSOLIDATED AND UNITED MINES OF CORNWALL. This is the title of some of the richest mines at present in Cornwall, England. They are located about two miles east of Redruth. The elevation of the surface above the level of the sea is from 200 to 300 feet. But the depth of the bottom of the mines below the level is about 1370 feet. The nature of the rock is primary clay slate, resting immediately on granite a short distance westward of the mines. The clay slate is intersected by numerous channels of porphyry, which have nearly the same direction as the mineral veins, and are often of considerable width. The porphyry appears also sometimes to form large irregular masses in the clay slate. Both rocks are traversed by veins of quartz and clay intersecting the metalliferous veins. In the Consolidated Mines the eight following lodes are extensively worked:-Wheel Fortune lode, Casvea lode, Deeble's lode, Old lode, Taylor's lode, Tregonning's lode, Martin's lode, and Glover's lode. In the United Mines, the principal workings are upon the Old lode, and about five or six others are more or less productive. Numerous smaller lodes, or "branches," occur also in both mines. The principal lodes are from two or three to seven or eight feet wide; and the "branches" are generally twelve or eighteen inches wide. The direction of the lodes varies from nearly east and west to about twenty degrees north of east, and south of west. The underlie of the principal lodes is from two to three feet per fathom north, that of the smaller ones about the same south. The ore is chiefly copper, occasionally native copper, blue and green carbonate of copper. Tin, or oxide of tin, also occurs, but not in very great abund ance. The produce of the ores averages 91 per cent. of fine copper in 100 parts of orc. The veinstone is cheifly quartz, of which many varieties occur. The accompanying mineral substances are generally "Gossun" (oxide of iron and quartz) in the back of the lodes, blende, iron, and arsenical pyrites in depth. The depths of the principal shafts are respectively 248 fathoms and 275 fathoms, although some of the others are scarcely of less depth. The average depth of the adit at the principal shafts is about 30 or 40 fathoms. The quantity of water varies from 2000 to 3000 gallons per minute. The height to which the water is raised is about 230 fathoms at the Consolidated Mines, and about 110 fathoms at the United Mines. The power employed in drainage consists of 9 steam engines; 3 of 90 inch cylinder; 3 of 85, 1 of 80, and 2 of 65. The water-wheel is 48 feet in diam eter. The average annual expense in drainage is about £12,700. The quantity of ore annually produced was a few years since about 16,400 tons of copper, and a few tons of tin. The produce in metal was 1,517 tons of fine copper, and a little tin. The total returns or value of which was £119,800. The total cost of the mine including lord's dues, was £98,500, and the total clear profit to the proprietors per annum £21,000. The amount of capital invested in the mines is £75,000. The interest on the capital invested has been 280 per cent. after paying back the original capital. The proportion of costs to returns exclusive of lord's dues, has been 78 per cent. About 2,500 persons are employed at the mines, of whom 1,450 are employed under ground. Their wages averages 3 English shillings per day. The produce of the mines is sold to the smelting companies in Swansea, South Wales. ANCIENT METALLURGY. Dr. Verey, of the School of Mines in England, has made an examination of some of the specimens of metallic workmanship which have been discovered by the celebrated Layard, in his researches amid the Ruins of Ancient Nineveh. The collection has been deposited in the British Museum. It consists of numerous illustrations of ancient metallurgy, such as vessels, weapons, and miscellaneous articles, clearly proving that the Assyrians possessed considerable skill in the art of working metals. The examination was made in the Metallurgical Laboratory at the Museum of Practical Geology, and a summary of its results is contained in the subjoined statement: 1. A portion of a bronze bowl, or dish, from Nimroud.-The surface generally had a green coating of carbonate of copper, which was crystalline where it was thickest. Below the thickest parts of this coating was a layer of red or sub-oxide of copper, also more or less distinctly crystalline. A portion of the metal free from crust was analyzed, and found to be composed of copper and tin in the following proportions: Copper Composition. 10.63 100-14. 2. A bronze hook from the same ruins.-The external appearances were similar to those of No. 1. Composition. 99.63 3. This was a very remarkable specimen. It was a small casting, in the shape of the fore-leg of a bull. It formed the foot of a stand, consisting of a ring of iron, resting on three feet of bronze. It was deeply corroded in places, and posteriorly was fissured at the upper part. A section was made, which disclosed a central piece of iron, over which the bronze had been cast. At the upper part, where it had been broken off, the iron had rusted, and so produced the crack above mentioned. The casting was sound, and the contact perfect between the iron and surrounding bronze. It was evident on inspection that the bronze had been cast round the iron, and that the iron had not been let into the bronze; and in this opinion I am confirmed by Mr. Robinson of Pimlico, who has had considerable experience in bronze casting. |