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Show THE CIIIL.1,N TUATIFIKD LIMH-STOAK FOH.UAflO-V. Editors Herald : I noticed in tho Herxld of the 15th, present, that you have republished from the London Alining Journal, of the 20th April, a letter written by your humble servant. I find the most important part of this letter omitted, and, no doubt, in consequence of the difiieulty of representing the illustrations illustra-tions iu the shape of diagrams. And, therefore, I will add a few words, which may to some extent assist us in explaining the object of the diagrams, which can be seen in the London JJin-iny JJin-iny Journal of the date specified, and in the Sciattijic t'rtss of the month of : May. The fissure veins in the Chilian limestone formation, alluded to in the above letter, were worked by tho writer wri-ter to a depth of 2,Q00 perpendicular perpendicu-lar teet, and some forty mines, on the same vein, were worked to about the same depth, proviug that this fissure was not only wotked to a groat depth, hut the extent or lenmli ws nlmnt 24.UU0 feet. Two thiida of this couid . bo traced on the surlace, and ihe rest was reached by smiting .-hat is through 1 d&ritus, lo a depth uf oOU to 400 feet, till the limestone was reached. The perpendicular depth (or tbe 2,-Guit 2,-Guit lectj was divided into six periods; lhat is of strati tied aud iiou-aLraiilied bauds of ruck, averaging from SOU to 000 I'eet in thickness, their position beiug almost horizontal. The interesting inter-esting point is: how did this fisMiro behave in going through these consecutive consec-utive series of stratified and nou-strat-itied bauda? Wherever a band of stratified limestone lime-stone was struck, the vein aiieraged from six to eight feet, and productive, throughout the forty mines, situated on the same ledge. herever a band of non-stratified rock was struck, the ledge pinched to one-eighth ot an inch throuah-nit every mine, and at the same depth from surface; sur-face; and this pinched portion of the ledge had to bo driven through, on the several occasions, and averaging from 800 to 000 perpendicular feet, through a hard, compact, un-stratific un-stratific j rock- The surface rock in the district of Chanarcillo, in Chili, was limestone, consequently the ledge was large and productive at surface; and the urst pinch occurred at ' about 300 feet from surlace, through- ' out tbe forty mines, aud so vke v rsa, repeated several times, until the depth of 2,600 feet was reached. In the first bonwzi and from the surlace to a depth of 300 feet throughout, through-out, in the forty mines, the ores pto-duced pto-duced were hornilver and two more of tho corneous class discovered by the writer, such as embolitc and bromide of silver, and classified by professor Breitbaupt, of Freiberg, in tbe year 1847. The greatest amount of iodide of silver ever seen was also produced in tbe first bonanzt, and tbe largest specimen spec-imen known was presented to the college col-lege of Freiberg by the writer in 1847; but subsequently stolen from the cabinet, cab-inet, and advertised for, with a heavy reward, but has never been heard of since. The second Lonanyi in this formation forma-tion changed completely the character of its ores, being mostly ruby silver ores, with mammoth chunks of native silver. The third bonani produced almost every class of tmtimonial sul-phurets sul-phurets of silver, and carrying iron pyrites in quantity throughout the vein; such not having been the ca?e in any ot the bauds of rock nearer the sur- My next letter iu tbo Mining Journal Jour-nal of London, will treat of the segregated se-gregated or strata veins in the limestones lime-stones of Chili, Spain and Mexico tbe class that mostly occurs in tbe limestones of Utah aad Nevada and therelbre will contain information more ' adaptable to these localities. I Henry Sewell. |