The chain of the Alleganies, which tra verses the United States of North Ame rica from N.W. to S.F., includes a con siderable number of deposits of iron, lead, and copper ores ; along with some ores of silver, plumbago, and chromite of iron. Attempts have been made to mine a great many of these deposits, but most of these have been unsuccessful, and abandoned for a while. Some have been since re-opened.
A bed of black oxyde of iron occurs in gneiss near Franconia in New Hamp shire. It has a power of from 5 to 8 feet; and has been mined through a length of 200 feet, and to a depth of 90 feet. The same ore is found in veins in Massachu setts and Vermont, accompanied by cop per and iron pyrites. It is met with in immense quantities on the western bank of the lake Champlain, forming beds of from 1 to 20 feet in thickness, almost without mixture, encased in granite. It is also found in the mountains of that These deposits appear to ex tend without interruption from Canada to the neighborhood of New-York, where An exploration on them may be seen at Crown Point. The ore there extracted is in much esteem. Several mines of the same species exist in New Jersey. The primitive mountains which rise in the north of this state near the Delaware, in clude a bed almost vertical of black oxide of iron, which has been worked to 100 feet in depth. In the county of Sussex the same ore occurs, accompanied with Franklinite. At New Milford, in Con necticut, a pretty abundant mine of sparry iron occurs ; the only one of the kind known in the Alleganies. The United States contain a great many iron works, some of which prior to the year 1773, sent over iron to London. They are principally supplied from alluvial iron ore. Under the article IRON, various lo calities of the ores have been cited.
The most remarkable lead mines of the Alleganies are those of Southampton, in Massachusetts, and of Perkiomen creek, in Pennsylvania, 8 leagues_ from Phila delphia. The first furnishes a galena, slightly argentiferous ; an ore accompa nied with various minerals, with base of lead, copper, and zinc, and with gangues (vein-stones) of quartz, sulphate of bary ta, and fluor spar. These substances form a vein which traverses several pri mitive rocks, and is said to be known over a length of more than 6 leagues. At Perkiomen creek a vein of galena is mined which traverses a sandstone, re ferred by many geologists to the old red sandstone. Along with galena a great variety of minerals is found with a basis of lead, zinc, copper, and iron. The mines of lead worked in Virginia, on the banks of the Kanahwa, deserve also to be mentioned. Under the articles GALENA and LEAD notice has been made of the other deposits of lead in the United States. None of the copper mines actually in operation in the United States seem to merit particular attention. The mine of Schuyler, in New Jersey, had excited high hopes, but after the workings had been pushed to a depth of 300 feet, they have been for some years abandoned. The ore, which consisted of sulphuret of copper, with oxide and carbonate of cop per, occurred in a red sandstone. No re ference is made here to the extensive native copper deposits of Lake Superior.
In some points of the Alleganies, de posits have been noticed of chromite of iron and graphite.-See CHEOBIE.
Coal-measures occur in several points of the United States, especially on the N.W. slope of the Allegany mountains, in Michigan, Ohio, and Missouri.