Page:The American Cyclopædia (1879) Volume XI.djvu/595

 MINER dent of Tufts college, Medford, Mass., from Ju- ly, 1862, to November, 1874, when he resigned to return to his former charge in Boston. He has edited u The Star of Bethlehem," has con- tributed to periodicals, and has been prominent as an anti-slavery and temperance lecturer. MINER, Thomas, an American physician, born in Middletown, Conn., Oct. 15, 1777, died in "Worcester, Mass., April 23, 1841. He grad- uated at Yale college in 1796. The next six years he passed in teaching, and in the study of law, which in 1803 he abandoned for med- icine, and in 1807 he commenced practice at Middletown. About 1809 a malignant epi- demic fever, called spotted fever, prevailed in the Connecticut valley, for which he pursued a new mode of treatment, making careful notes of his cases. In 1823 he published, with Dr. William Tully, "Essays on Fevers and other Subjects," and in 1825 a treatise on " Typhus Syncopalis." His autobiography appeared in the " New Englander," vol. ii., p. 19. MINERAL, a N. E. county of West Virginia, separated from Maryland by the North branch of the Potomac river, and intersected by Pat- terson creek and other streams; area, about 550 sq. m. ; pop. in 1870, 6,332, of whom 378 were colored. It is crossed by several mountain ridges, between which lie picturesque and fer- tile valleys. The Baltimore and Ohio railroad runs along the N. and W. border. The chief productions in 1870 were 50,915 bushels of wheat, 13,257 of rye, 71,895 of Indian corn, 29,331 of oats, 8,891 of potatoes, 23,406 Ibs. of wool, 52,078 of butter, and 5,104 tons of hay. There were 1,333 horses, 5,172 cattle, 6,429 sheep, and 2,563 swine. Capital, New Creek. MINERAL DEPOSITS. The useful minerals occur in a variety of forms and conditions, and the deposits which are composed of or include them may be classified into superficial, stratified, and unstratified deposits. I. SUPER- FICIAL DEPOSITS. In these, the materials are yet unconsolidated, and have been washed down from cliffs and mountain slopes com- posed of rocks that contain metals, ores, and gems, either in veins or irregularly dissemina- ted. This category includes the gold of the surface deposits associated with the gold-bear- ing rocks of California, Colorado, Australia, the Ural mountains, &c. ; the platinum of Ore- gon and Siberia; the "stream tin" of Corn- wall, Banca, Australia, and Durango ; the dia- monds of Golconda, Brazil, and South Africa; and the rubies and sapphires of Ceylon. From such deposits all the platinum, all the diamonds, and probably nine tenths of all the gold in use have been procured. The working of these deposits constitutes the simplest form of mi- ning, viz., washing with water. The minerals obtained from them are usually distributed very sparsely through the rocks in which they primarily occur ; and as in the course of ages, by frost, sun, rain, and ice, these rocks have been comminuted and washed away, the met- als and precious stones they contain have been MINERAL DEPOSITS 577 sorted and concentrated by the action of water, so that in many instances they are gathered with little labor. By the Spaniards, the su- perficial deposits containing gold are called placers, and the working of these deposits has come to be generally termed placer mining. II. STEATIFIED DEPOSITS. The useful miner- als sometimes form entire strata, such as beds of coal and iron ore ; and they are sometimes disseminated through sedimentary rocks of which they form a larger or smaller part. In this latter category are included the clay-iron- stone of the coal measures, which forms no- dules thickly set in beds of shale, and the cop- per in the copper schists of Mansfeld, in the triassic sandstones of New Mexico, and in the sandstones and conglomerates of Lake Supe- rior. III. UNSTRATIFIED DEPOSITS. 1. Erup- tive Masses. Formerly most of the deposits of crystallized iron ore (magnetite and specu- lar iron) were supposed to be eruptive. We have learned now that they are for the most part only stratified deposits very much dis- turbed and metamorphosed. Such is certainly the character of the iron ores of Missouri, Lake Superior, and the Alleghany belt, all of which may be shown to be simply changed and disturbed beds of iron ore, once deposited in nearly horizontal sheets. The famous de- posits of iron ore of the island of Elba and of Nizhni Tagilsk in Russia are still believed to be eruptive, but it is probable that they will hereafter be shown to belong to the same cate- gory with our American crystalline iron ores. Iron is a common ingredient of volcanic rocks, and in some instances the quantity contained in them is so great that they may be termed low-grade iron ores; but such cases are ex- tremely rare, and it is very doubtful whether there are any deposits of metals or ores of economic value which can properly be regard- ed as eruptive masses. It is scarcely necessary to say that the great deposits of metallic cop- per found on Lake Superior, and supposed at one time to be the result of subterranean fu- sion, are now clearly shown to be the products of chemical precipitation, and to have been de- posited much as copper is precipitated in the electrotype process. 2. Minerals dissemina* ted through Eruptive Rocks. Of this class of deposits, magnetic iron contained in volcanic rocks and the copper in the amgydaloids of Lake Superior may be taken as examples. In Japan the iron derived from decomposing vol- canic rocks is collected and used, and large quantities of copper are obtained from the so- called melaphyres of the Portage Lake district on Lake Superior ; but as a general rule igne- ous rocks are very barren in useful minerals. 3. Contact Deposits. The plane of junction between two rocks of different kinds, such as igneous and sedimentary rocks, is frequently the place where metals or ores have accumu- lated and form concretions, strings, or sheets. Examples of this may be seen in the deposits of copper at the junction of the trap and ash.