Page:The American Cyclopædia (1879) Volume X.djvu/260

 254: LEAD ally the same as those already described as com- mon to the northern mines. The openings on the vertical fissures vary from the capacity of a cubic foot to 10 or 12 ft. square, and when very small are called pockets. They do not pre- serve a uniform course, but connect one with another by passages filled with material dif- ferent from the walls, and extending toward every point of the compass. Valle's mine in St. Francois co. and Perry's on its extension S. present a remarkable network of veins spread over an area of about 1,500 ft. in length by 500 in breadth, ranging N. W. and S. E. They are also examples of mines of a more perma- nent character than are found in the northern lead region. Valle's mine was discovered in 1824, and it is believed has been worked ever since without interruption. Three series of caves are found, the second set 18 or 20 ft. below the first, and the third about 8 ft. be- low the second. The middle set has been most worked. They run out in every direction, and in some instances communicate by chimneys with the series above or below. They are filled with clay, loose rock, and ore, the lastoften an intermixture of galena and silicate and carbon- ate of zinc, which requires roasting and wash- ing to prepare it for the furnace. Dr. Litton was of opinion that three fourths of all the lead obtained in Missouri had been from clay diggings overlying the rock. These operations have often been highly productive, but were carried on without system and without capital by men who had no interest or ability to pros- ecute the work in the rock, and thus the more permanent deposits have been passed over. In some localities in Missouri lead has been found in the coal measures, and has been worked in the sub-carboniferous limestone. In Moniteau co. a bed of dense cannel coal 40 ft. thick is traversed by a network of veins crossing at all angles filled with galena, zinc blende, and calc spar. There are numerous deposits of lead ore in the Atlantic states, but none of them have as yet proved to be of economic importance. (See Whitney's " Mineral Wealth of the United States.") In the belt of metamorphic rocks which extends along the S. E. flank of the Ap- palachian chain, there are a number of lead veins, many of -which have been worked, but subsequently abandoned, owing to the small quantity of the ore, or the difficulty of sepa- rating it from the associated minerals, or the expense of mining in hard rock. As some of the deposits are highly argentiferous, it is not improbable that work on them may be resumed with profit at some future time. Among the localities best known in the New England states may be mentioned Shelburne, Eaton, and Warren in New Hampshire, Northampton and vicinity in Massachusetts, and Middletown and Plymouth in Connecticut. Some of the ore from the Shelburne mine gave 84 oz. of silver to the ton of lead, and from the Warren mine 60 to 70 oz. to the ton. The mines in the neighborhood of Northampton, Mass., were worked as long ago as 1765. The vein here is extensive and well defined, but is not very pro- ductive, and owing to the expense of mining work on it, though often resumed, has been as often abandoned. At Middletown, Conn., the existence of lead ore was probably known in 1651, when a license was granted to Gov. John Winthrop to work mines of this and other specified mineral productions, with particular reference to any he might discover near Mid- dletown. There is no tradition of the time when the mine was first worked. The ore is highly argentiferous galena, but not abundant. Shipments made to England yielded 25 to 75 oz. of silver to 21 cwt. of lead; and what was remarkable, a peculiar fine-grained variety of the ore, such as is usually found to be most argentiferous, proved to be only one third as rich in silver as the coarsely cubical ore. The vein consists chiefly of quartz, often in crystal- lized plates or combs, with some calc spar, sulphate of baryta, and fluor spar, also blende and iron and copper pyrites. It is from 10 in. to 3 ft. in thickness, and is included in silicious and micaceous slates, with the dip and direction of which it appeal's at the sur- face to coincide. Active operations at this mine have long since ceased. In Dutchess co., N. Y., explorations were made for lead in 1740, and during the revolutionary war the committee of public safety sought to obtain supplies there. Veins of argentiferous gale- na are found also in Columbia, Washington, and Rensselaer cos., but have never proved productive. They traverse the strata near the junction of the metamorphic slates and lime- stones. The principal one is the Ancram or Livingston mine in Columbia co. On the other side of the Hudson river lead mines have been worked at various localities in the unaltered Silurian limestones and sandstones ; but these, too, have all been abandoned as unprofitable. The most productive among them were in the Shawangunk grit of Ulster co., which overlies the Hudson river slate group. On the W. slope of the Shawangunk mountain, at Ellenville, several nearly vertical veins have been followed into the hard sandstone, the strata of which and the direction of the mountain ridge they cross nearly at right angles. The principal one of these yielded in 1853 galena which produced about 459,000 Ibs. of lead, and 60 to 70 tons of pyritous copper, 50 tons of which produced 24'3 per cent, of metal. The vein was unlike the true veins of the metamorphic rocks, hav- ing no gangue or veinstones, but wherever pro- ductive filled between the walls with rich ga- lena and pyritous copper, the former sometimes being 5 ft. thick unmixed with other matters. In places it contracted to a knife-edge seam in the hard sandstone, and again opened out in hollow fissures, one of which, extending to more than 100 ft. in depth, with an equal hori- zontal range, has never been completely ex- plored. It was partially filled with tough yel- low clay, in which were imbedded loose frag-