Arkansas true Democrat., 1861-10-03

 from l5 to 30 feet through; 1t seems to be com- posed of porous colcareous matter, in which some sulphuret of lead, sulphuret of zine, black iack) and bitter spar, (magnesian hmestone), is disseminated. After this barrier Is broken throu gh the miner reaches the < sheet mineral, lying, not perfectly leve but waving somewhat with the irregular, corroded surface of the rock on which it has been deposited, and mixed, more or less, with talow clay" either red or white, which is tenaceous, unctuous clay, sometimes ferruginous, in certain states of dry ness cuts like tallow or soap. There are also, various minerals, either amorphous (l. e. with out any regular geometrlcal torms), or crystal lized; such as pearlspar, bitter spar carbonate of lead, carbonate and silicate of zine. suphuret of zinc, with occasionally crystals of sulphate and phosphate of lead, disseminated with the calcspar. the principal vein-stone accompany. ing the galena. The so called |" black]ack rock,"G e. a rock in which sul lphuret of zinc is largely disseminated), is considered a good indication of lead ore.
 The material passed through in sinking the shaft. is mostly white chert in displaced and confused masses. This chert is often light and porous-almost possessing the structure of pumice.
 Three tiers of sheet-ore have been success ivey passed through; that at an average depth of 65 feet from the grass" has proved, as yet, the most productive. Ore has been reached, however, within 10 and 20 feet of the surface.
 The horizontal sheets of lead ore vary ln thickness from fractons of an inch to feet, and even, in some extraordinary instances, to 3 feet. The average thickness may be put down at to 10 inches. They are often so rich that it is not uncommon, after shaft has been fairly sunk to the level of the ore, for two men to raise from 1000 to 2000 pounds and even sometimes 5000 to 1000 pounds, in six or eight hours 30,000 to 50,000 pounds have been raised out of the Hopkins mine by 20 men, each man averaging from 400 to 300 pounds a day.
 At the Frazer shaft, from a quater acre lot, 10000 pounds were taken out; and, from all tie Frazer claims, up to the present time, comprls- ing 10 acres, 100000 pounds of lead ore have been raised. The total amount of ore raised in the last two years is about 800, ,OO0 pounds.
 The ore, as has been said, lies mostly in hor- izontal spaces, conformable with the bedding rock; but nevertheless, there are crevces hay ing connection with the ore, the bearing of which is nearly north and south, opening occa- sonally into cavernous spaces, precisely analo- gous to the ore bearing veins in other parts of the State and in Wisconsin and Iowa; but these are either entirely barren of ore or contain only small quantities. My impression is, that the lead ore once occupied these north and south crevces, and was subsequently removed, in part or in whole, into its present bed by tcanspos ton, analogous to that known to minerologlsts under the name of the pseudomorphous process, by which one mineral Is removed, which another takes its place, assuming often the form of the first mineral instead of the usual form belong ing to itself The term analogous" is used, because the lead ore here connot exactly be considered to occur in false form, or one be- longing to another mineral; in this instance, believe, it only took the place of the amor phus rock, therefore 1t not lnhrated into pre-exiStng geometrlcal mould; If may so eX- press it, but had freedom of space sufficient to assume its usual cubodal structure. That 1t should be deposited like limestone or sand stone, is altogether improbable and contrary to the usual nature of such ponderous and diff cult solube mineral
 The lead bearing rock is not very fossilfer ous, but there can be distinguished the Orttis criajstfia, Productus cora, and other fossils ot the cherty barren limestone division of the sub carboniferous group; not, however, belonging to the Archimedes and pentremital group, as has been suggested.
 Though the profitable discoveries of lead ore at the Granby mines, have hitherto been c0nfn- ed to about one mile square; still they attracted population, in two years, of 5000 people, to section of land before almost neglected even by the farmer, and which now, with the untavora- ble circumstances, under which the mining claims are held, (being part of tract condition ally ceded to one of the proposed Pacific rail road roues), has, nevertheless, in that short space of time, converted wild prairie into popuous town, full ofenterprise and industry.
 It should be observed, too, that the surface iOdi time the mines were started, than they are in many localities that may be pointed out in the above counties in Arkansas, where the same formation exists and where the cherty materials, thrown out from excay yations for wells, cannot be distinguished from the rubbish rock at the mouth of the Granby shafts. 1 may add, too, that, in all these counties, surface ore has occa- siorally been found under circumstances smi- lar to that in which they were first discovered in Newton county. But still the search after lead ore may be precarious, and lead to many disap- pontments; since ore is only locally and not uniUersally distributed through the rock; hence 1t requiers not only general knowledge of min erals, but special experience in this, particular rock formation, to sink shaft successfully on ore even though the miner may have surface indications to guide him.
 If the ore should be found in sheets, as in Missouri, the thickness of the lead bearing rock is not matter of such moment but if 1t should occur in veins or odes, then that question as sumes importance.
 In the northwest part of Arkansas I d:d not fnd at any one place, more than one hundred feet of chertv, barren limestone exposed; but this is, probably, not its entire thickness. In Searcy county, solid cliffs of more than 200 feet of this rock have been observed. In follow ing vertical veins through this rock, the black shales of Hickory and Sugar creeks will be en- countered in this rock it is not likely that ore will be found in sufficient quantities to be prof. table to work; but this shae is of no great thick ness 38 feet is the greatest number of feet l have seen exposed; it is not likely that the whole will exceed 50 feet. This passed through, solid limestones will be again entered, in which the veins may also prove productive.
 The chances, then, are favorable for the oc- currence of productive lead mines in the north west part of Arkansas, north of the boundary line of the millstone grit and its underlying shales
 CARROLL COUNTY.
 As yet, only the eastern portion of this county has been examined. The lead ore of this coun- tv. occurs in the cotemporaneous formations ot maouesian limestones, with occasional inter- justification of sandstone and slceous lime stones. oyeraid towards the summits of the hills, bv the encrinital limestones and marble rock, canned with chert. The diggings have been somewhat deeper in Carroll than Tn Madison county. but still quite limited, consisting of a few shallow trenches on the hillside, and one