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Show GEOLOGICAL FORMATION OF UAH ML.KS. THS ROCK FOBMATTON. In my last I gave you the genera; topography of the mineral belt of Lhi? region, and propose in this letter to enter into & more specific description of the geology of the belt, character of ores, etc In the first place, the rock of this entire region is. generally speaking, limestone, although this is frequently intersected by belts of granite, gran-ite, porphyry, slate, quartzite, sandstone, sand-stone, and various kinds of meta-morphic meta-morphic rock, and some one or more of these in almost every instance indicates indi-cates the limit and direction of the ore lodes. The general principles o! geology are confiiined by practical ex perience, bat the pick and shovel dai:j demonstrate that the science with respect re-spect to mining, in minute particular? and dogmatic details, is pureiy speculative specu-lative and in many respects wildly so. Thus the failure of a lew tissurc lodes of argentiferous ere in the S:aie of Nevada in a lioicstoie formation, was considered a sufficient basis to induce in-duce scientific as well as boiius mining experts to promulgate tho general theory the-ory and alHrm it under oaiii as witnesses witnes-ses in minicg 6uits, that lodes were always narrow and shallow in such a formation, when the fact is that silver mines arc as large, deep and rich in lime as in any other kind of rock. The Charuacilio mines in Chili, worked for centuries, the immensely extensive and rich mines at ZomLrorete in Mexico, Mex-ico, and many others oi' the best mines on the two continents, are in a lime country rock fornia'.irn. The larL-st, richest and longest successively worked mine I ever saw that of Guadalupe de los Reyes, in Northern Mexico is in limestone. In truth lime, excepting quartz, is the only kind of rock that forms the gaoguc or matrix o'' silver lcdea. THE COTTONWOOD D 1ST If CTS Are, as yet, by fur the richest and most extensive -of the depositories of silver ore yet discovered in the Territory, Terri-tory, and the mineral belt that crosses the divide between the two Cottonwood Cotton-wood creeks is entitled to the appellation appella-tion of the Cormtock of Utah. This belt is by the roadway about tw:nty-tivc tw:nty-tivc miles from this city, near the summit and on the western slope of the asatch range of mountains, and at an average elevation of 9,500 feet j above the sea level. Tho vein rock of i the mountain is granite from its base ! until within two miles of the summit, when lime predominates, intersected by veins of quartzite in belts of sandstone, and in this last, which abuts against the granite, he the ore lodes. The grand silver -belt is in the form of a parallelogram, as fur as developed about two miles in length by 3,000 feet in width, bearing about twenty-five degrees north of cast, and within it are located the richest mines of the Territory. Terri-tory. The white sandstone of this parallelogram is the limit of the ore deposits, which exist throughout its extent, but not continuously in a horizontal hori-zontal direction. The inclosing and gangue rock is continuous, but, as in the Nevada Com stock lode, the greater part of it is barren horizontally in different dif-ferent places, but like it, as far as developed, de-veloped, shows no failure of a depth of ore, although in many places the dip of the lode 13 thrown out of its general direction or dislocated by some natural cause. I am entirely confident that in less than five years ihia'uiineral lode will rank with ihe richest ever discovered in any part of the world. Some of the best lodes were discovered dis-covered by following a mere min-oral min-oral stain, as in the caso of the Emma with reference to its present large and rich body of ore. On the surface, and lor a depth of about twenty l'eet, there was found a considerable body of medium grade ore not over ten feet in length and tapering to the outcrop aud supposed sup-posed bottom. The body of ore giving out at this depth, the mine w:is abandoned, aban-doned, but ultimately, after fallowing now a stain, then a narrow team of ore, and sometimes only a suppositious direction of barren rock, in a zigzag downward course of ninety feet, tliu grand body of ore that was found that lias given the mine its great reputation. It i.s evident that in all of ilu' mines ofthisb.lt ihe figures ttii e formed mid filled i'rom below. In the Montezuma. Monte-zuma. Savage, l"lagst3fl", lJavenport and Enterprise mines the outcrop was very narrow, and the loHes of ail of them have continued to improve with the depth attained. In llie L'li'g'tafT and the Davenport, at a depth of Km loot the ore lodes are very large, and the Enterprise, at the present extreme depth of its main shuft, seventy-five feet, has a lode five feet, in width of very fine ore. This mine can be readily read-ily traced by stains and small deposits of ore lor several hundred lect on the surface. The outcropping indications of all these mines seem to have been spewed to the surface from the immense im-mense mass below, finding issue wherever wher-ever the cap rock made it possible. A narrow guage railway will probably be built duncg the present year from those mines to the valley below, a distance dist-ance of ten miles, to a point at which a connection will be made wi'h the I". S. railroad. The mines, not withstanding withstand-ing the great depth of snow in winter, can be worked very economically. They are dry to a depth far below any of the present workiog, and the ore is so soft and crumbly that powder is seldom sel-dom required to be used in its extraction. extrac-tion. tia.lt Like correspondent of the JtUsiuri Republican. |