learned; so that we can decide the question as to the value of the mine and its productiveness.

A pretty full description of this mine is contained in my final report on the Geology and Mineralogy of the State of New Hampshire (pp. 102, 103, and 228), insomuch that it will not be necessary for me to enter into a very detailed account of the geographical character of the country, or to describe all the minerals which occur there. I shall therefore limit myself in the Report, to a very brief statement of the situation of the mine, and the minerals which occur in the veins; while a more full account of its economical value will be given, and the method of working it will be detailed.

Shelburne Lead Mine is situated in a northwest part of the town, in a gorge, two miles northwest from the house of Mr. Burbank, and in the bed of a small stream, which comes down from the mountains and runs through the gorge.

The veins are included in compact mica slate rocks, and are quite irregular in their dimensions, and in their course through the rock. They are what miners call pipe veins, and have very

rich branches of pure ore at different points in their course. The general direction of the lead veins is N. 80° W., S. 80° E., and they dip to the northward about 70° from the horizon. There is, however, such a diversity of directions and dips of these veins,

that they often cross each other, and evidently must unite in several places below the surface. Hence, it is practicable to work two or more veins at the crossings, where the bunches of ore are much heavier or more frequent. One of the veins runs N. 86° E., S. 86° W., and dips to the N. 75°. Another near it runs N. 56° W., S. 56° E., and dips to the N. E. 86°.

The first vein is from 3 to 8 inches in width, and the second is 4 inches.

The distance apart is 5 feet 3 inches. Now it is obvious that these two veins will meet each other in two places, one meeting at the junction of the lines of directions, and the other with that of their inclination or dip.

There are about half a dozen veins in the ravine within the limits of 36 feet. Some of those which I surveyed while employed by the State, were covered with gravel and water, during our recent visit; and some of those now uncovered and wrought, are new ones. On the northern side of the ravine is a singular varierty of galena, being fibrous in its structure, and very compact. It resembles somewhat the sulphuret of antimony, but is really an argentiferous sulphuret of lead.

The width of the veins varies so much in different parts of the course, that it is impossible to give an accurate measurement; but it might be stated generally, that they are from an inch, to 8 inches wide, and that the black blende, or zinc ore, occurs mostly in the pipe veins and not in the branches, which occur in their course at frequent intervals, as represented in the woodcut in my final report on the Geology of New Hampshire, p. 103, which cut is a drawing of the veins on the south side of the ravine. Iron pyrites is scattered through the lead veins in crystals and in groups, filling cavities. Brown spar is the vein-stone or matrix of the lead ore. Copper pyrites occur occasionally, associated with the black blende or zinc ore. It appears that the black sulphuret of copper is the coloring matter of the black blende; as a notable proportion of copper has been found in it by analysis. It is probable that your company will limit its operations to the extraction of argentiferous lead, and, therefore, it will be unnecessary for me to enter into any details concerning the manufacture of the zinc. Your smelting works will be erected near the mine, and the ore will be reduced to pig lead, and sent to market in that state, or you will take it to some convenient place for cupellation, so as to separate the silver from the lead.

With regard to the practicability of working the mine, I would observe that it can be done with a reasonable expense in preparation. A dam must be constructed at the head of the falls, and a wooden trunk or aqueduct is to be placed so as to carry the water one side, or over the head of the miners who may work the veins in the ravine. This method has been

It

adopted in one mine at my suggestion, and works very well. is the cheapest you can follow, and will afford you the opportunity of using the water from the aqueduct in washing the ores. The distance from the top of the falls to beyond the mine, is 105 feet, and the slope is 7° 20. It is evident that the water may be run off in a very swift current, so that it cannot freeze or accumulate. The present width of the stream is from 1 to 2 feet, and its depth 2 inches; but in the freshets this little stream becomes swollen into a powerful torrent, and fills the ravine to some depth, probably three or four feet. Therefore it will be needful to make the aqueduct a trunk of stout plank, and to have it well secured. Below the mine about 20 or 30 rods, the stream unites with a branch coming in on the west side of the hill, and thus it is of sufficient power to move all the machinery required in working the ore. I placed a level log on the bottom and secured it tight, and then gauged the water and found it to be 2 inches in depth, on a dam or capling of 3 feet in length. Look in the tables of discharge of water, and you will find the quantity discharged by this stream.

In order to form some approximate estimate of the quantity of ore a miner could raise per day, we employed two men in blasting out ore on one of the veins, noting the time when they commenced operations, and when they finished. The ore was weighed, and thus from 9 A. M. to 12, noon (three hours), two men raised 160 pounds of fifty per cent. lead ore, which would be equal to 1,280 pounds in twenty-four hours. One half of this weight being lead, it would amount to 640 pounds, which would be worth for lead at three cents per pound, $19 20; and if the lead contains five pounds of silver per ton, 640 pounds will contain 17 pounds, which will be worth $30. Hence, the metals raised by two men in 24 hours, will be worth $49 00. The expense of smelting the lead and separating the silver, must be deducted from this; but I have no data applicable to the kind of works you are about to erect-the cost will be comparatively little.

In this experimental trial it should be observed that only one vein was worked upon, and that the miners had to work at a disadvantage; there having been no systematic efforts made, as in regular mining operations. The result to which we must necessarily come in considering this mine, and the experiments made in the ores is, that it can be wrought at a handsome profit over the expenses of mining and smelting. Therefore I unhesitatingly recommend your company to begin regular and systematic mining operations, and to erect your furnace for smelting into pig lead. It is to be considered whether you will separate the silver from the lead yourselves, or sell it to European manufacturers who will pay, on assay, for the silver in the lead. Wood

suitable for smelting operations you have in abundance round your mine, and the road to Portland is very good, so that there is no difficulty as to transportation of the lead to market. The cost of transportation of merchandise to Portland is small, and that of lead will be still less. A road is required to the mine, and your agent has already begun to construct it, and probably has it now ready.

ASSAYS OF SHELBURNE LEAD ORE.

Sample No. 1.-500 grains of the silver galena, reduced to metal, yielded 380 grains of lead, which on cupellation gave 0.99 grains of silver or nearly the ore, or lbs. on the lead. The lead amounted to 76 per cent. One ton of the lead will yield 5% of silver.

300

380

Sample No. 2.-500 grains of the crystallized galena mixed with iron pyrites, on being smelted yielded 330 grains or 66 per cent. of lead, and the lead cupelled yielded 0.7 gr. of silver or 4 ton of lead.

per Sample No. 3.-1000 grains of crystallized lead ore yielded 690 grs. of lead or 69 per cent., the silver separated amounted to

grs., 2.87lbs. per ton of lead. This sample was of a more blue color than the others, and more like common galena. It came from the middle vein. You are aware that most of the lead may be saved in cupelling lead for silver, the litharge being run off and saved, and sold in that state or reduced back to metallic lead. When red lead and litharge are in demand, as they are at our numerous flint glass works, there will be no difficulty in disposing of a considerable quantity; and when you furnish more than will sell, you might easily receive the lead and sell it in that state.

I ought to say in closing, that much of the success of mining enterprises depends on the management of the mines and works, and in the relations of the capital invested to the amount of profit that may be reasonably expected. You will of course keep clear of the gambling operations of the stock market, and depend on your mine for remuneration for the labor, capital, and skill, devoted to working it.

I would suggest the propriety of purchasing the rich alloys and mixtures of copper and silver which are brought from some of the mines on Lake Superior, and to separating the silver from the copper by means of your argentiferous lead. For it will cost no more to separate a large than a small proportion of silver from lead, the same amount of fuel being required in the operation. Respectfully your obedient servant,

CHARLES T. JACKSON, State Assayer of Ores and Metals.

VOL. I.-16

P. S.-I am making some researches on the fibrous galena, which are not yet completed, and will communicate the result to you hereafter. You have in the report all the facts which bear on the economy of mining at Shelburne, and the cupellation of the lead for silver. I would suggest, if you intend erecting cupelling furnaces, that you should procure some good German workmen from Androesburg mine in the Hartz mountains.

ANALYSIS BY A. A. HAYES, ASSAYER OF THE STATE OF

MASSACHUSETTS.

Result of Analysis and Assays of two samples of Galena, designated as Keg of Ore and Package of Ore, received from Captain Colby.

Keg of Ore.-This sample presented masses of clean ore composed of sulphurets of lead, zinc, and iron, with some pyritous copper. The rock which adhered to the ore was principally brown spar, or carbonate of iron mixed with calc-spar; both rendering the reduction of the lead very easy. An average obtained from the sample in the keg was reduced to powder for the assays and analysis; 100 parts of this sample afford 567 lead by analysis.

An assay ton, representing 2000lbs. of this sample gave with fluxes 1100lbs. of silver lead. This is the largest quantity which can be obtained. Besides the lead, an alloy of metals and sulphur was obtained which will be examined hereafter.

An assay ton of the silver lead gave 3lbs. of pure silver. Thirty-six hundred and thirty six pounds of this ore will afford 2000lbs. of silver lead, which will contain 3,2lbs. of silver.

ΤΟ

Package of Ore. The whole of this sample contained much sulphuret of iron, blende and pyritous copper, besides adhering rocks; 100 parts by analysis afforded 43 lbs. lead. An assay ton of this ore gave 780lbs. of silver lead; this being 33 per cent., while the analysis affords 43 per cent., and shows the greater difficulty of working ore like this sample, containing a number of sulphurets.

silver.

An assay ton of the silver lead gave 3% of of pure Fifty-one hundred and thirty pounds of this ore, are required to produce 2000lbs. of silver lead, containing 3 lbs. pure silver. Respectfully, A. A. HAYES,

State Assayer.