separated from the gangue and from the zinc blende by hand-sorting and jigging. The early operators aparently mined between 1,000 and 1,500 tons of ore. Again, beginning in 1899, the North American Ore & Metal Company reopened and operated the same mines in Sevier County for several years. During the first two years 1,140 tons of ore were removed, the ore being a mixture of zinc blende, galena, chalcopyrite, and a little pyrite, with wellemite and smithsonite sparingly present. An analysis of a sample representing about 5,000 pounds showed the concentrates to contain 82 per cent lead. One shipment of 57,000 pounds to Joplin showed 55.16 per cent zinc and iron 3.91 per cent as the average of four separate analyses. The Kellogg mine, located in Section 30, Township 3 north, Range 11 west, Pulaski County, which has been worked intermittently since about 1840, has an estimated yield up to the present time (December, 1926) of seventy short tons of lead and silver concentrates valued at about $6,000.00, and forty short tons of zinc concentrates valued at about $1,000.00. As approximately $225,000.00 has been invested and spent on the mine during the years it was worked, a considerable loss has been entailed. There are 8,000 feet of shafts, tunnels and raises in the mine, the main shaft having a present depth of 1,125 feet. According to T. B. Comstock, Assistant State Geologist, who made a study of the minerals in the west-central Arkansas district in 1888, the lead and zinc situation of west-central Arkansas is as follows: "The lead and zinc ores occurring in the mineral belt in portions of Pulaski, Saline, Garland, Montgomery, Polk, Pike, Howard and Sevier Counties are so closely associated with silver that it is unnecessary to consider them separately. Wherever there has been a discovery of the 'gray copper' silver-bearing minerals in more than filmy deposits, galena has always been found, and sphalerite or zinc blende is an almost invariable accompaniment in the same or neighboring ore bodies.". The districts in west-central Arkansas which at one time were thought to contain commercial lead and zinc ores, were the Kellogg area in Pulaski County and the tract southwest of the Ouachita River lying between Broken Rock and Blue Mountain axes in Montgomery, Howard and Sevier Counties, and crossing the southeastern portion of Polk County. Galena is probably the only mineral which occurs in commercial quantities in this region, at least so far as is known. Although none of the lead mines are being worked today, it does not seem impossible that lead deposits may be discovered in this area which will merit development. The Housley mine, located near Point Cedar, Hot Spring County, has produced a small amount of high grade lead ore and as yet has been little developed. The only ore of zinc that has been mined in west-central Arkansas is sphalerite, or zinc sulphide, or blende. There is also a little calamine or zinc silicate, some zinc carbonate or smithsonite being found with the sulphide ores, but usually not in any quantity. Other than the zinc product of the Kellogg mines, Pulaski County; the Silver Hill, Sevier County, and the Silver City mines, Montgomery County, a small amount of zinc has been detected in Polk County, but no ore bodies have been reported as yet. Another probable district is the area north of the base line upon the Saline River drainage, particularly in the basin of the north fork of that stream. *North Arkansas Area History and Occurrence-Lead ore was used by early explorers in northern Arkansas for the making of bullets. The occurrence of lead has been mentioned by writers as early as 1818. In 1834 Featherstonhaugh mentioned that a mine was in operation on Strawberry River, and ore was smelted at Lead Hill, northern Boone County, between 1850 and 1860. The industry revived about 1870, but the cost of transportation was so great at that time that the operations were abandoned. A zinc smelter was erected at Calamine, Sharp County, in 1857 and operated until the Civil War. Smelting was resumed during 1871 and 1872. Prospecting began about 1886 and in 1899 a larger number of prospectors were busy in north Arkansas. The greatest development of zinc and lead mining in the history of the State occurred during 1917-1918, when the price of lead and zinc rose to a very high figure and stimulated mining as never before. After the war, the prices dropped and mining practically ceased. At the present (December, 1926) there are indications of a revival of mining, (three mines are now in operation). The depletion of the Missouri, Kansas and Oklahoma reserves will very probably result in a progressive development of the Arkansas fields. The lead and zinc area of northern Arkansas has never been specifically defined. It includes principally Marion, Boone, Newton and Searcy Counties, and to a lesser extent Baxter, Stone, Izard, Independence, Sharp and Lawrence Counties, and covers an area of possibly 1,600 square miles. The distribution of the mines and prospects in the first four counties is shown on the accompanying maps. This area lies in the Ozark Plateau region of Arkansas or, more specifically, partly on the Springfield Plateau and partly on the Salem Plateau. The region is principally a limestone and a dolomite area, which has been dissected by the irregular water courses and presents a rough and broken topography. The rocks lying as they do on the southern flank of the Ozark Uplift, usually have a nearly horizontal position or have a slight regional slope to the south. *Historical data according to G. I. Adams, U. S. Geological Survey Professional Paper No. 24. The surface formations in the southern portion of the zinc and lead area of north Arkansas include the Winslow formation and extends through the older formations, including the Cotter dolomite (see table). It is noticeable that the younger formations have, however, been progressively worn away as one passes north to the Ozark Uplift, where one finds only the Cotter dolomite. Key sandstone (St. Peter sandstone) (?) Top of Yellville limestone (Cotter dolomite) U. S. Geological Survey Profes *E. O. Ulrich, "Determination and Correlation of Formations." sional Paper No. 24. Practically all of the zinc and lead ores occur either in the Boone or in the Cotter formations. Of these two, the Cotter contains the greater concentrations of ore, and the deposits in it are more widely distributed than those in the Boone. The principal ore deposits in the Boone formation occur in the southwest portion of the field. The ores may be classed according to their method of occurrence, as follows: 1. Bedded deposits which, for the most part, were deposited with the rocks in which they occur. 2. Vein deposits of later age than the rocks in which they These may be classed as: occur. ores. a. Fault or fracture deposits. b. Deposits associated with brecciated rock masses which have formed along underground water courses. 3. Alteration products, principally carbonate and silicate zinc Bedded Deposits.-The bedded deposits of zinc ores are found as disseminated ores associated with chert or dolomite. As a rule, this type of deposit is richer in the trough of the synclines than elsewhere. These deposits are usually fairly closely confined to some specific bed which may sometimes be traced for miles and usually are remarkably even in thickness and richness. It is probable that the vein deposits were derived from these disseminated bedded ores. The bedded ores as a rule are found in localities where ground waters are not active or where the bedded ore is contained in rock which is only slightly permeable by water. Bedded deposits are not infrequently exposed along the sides of deeply eroded valleys. Examples of mines in bedded zinc ores are Marble City mine, McIntosh mine, Little Rock mine, Lion Hill mines, Virginia mine, and Roberts mine. These deposits, although of great extent, do not ordinarily run more than 6 per cent zinc ore concentrates and have furnished very little of the total ore produced. By drill holes and shafts it has frequently been found that there are two and sometimes three strata, all containing bedded zinc ores. These, however, are often separated by intervals of eighty to one hundred feet. Vein Deposits.-The vein deposits include both fault deposits and those filling brecciated beds which have been permeated by underground waters of meteoric origin. These waters penetrated the earth, dissolving limestones and dolomites, and in some cases formed caverns which caved in and have been filled with irregular rock fragments and created brecciated mineralized masses. The faults in the lead and zinc area frequently break the entire series of rocks exposed. They are normal, reversed, and lateral faults and extend from comparatively short distances to many miles. The fractured zones vary from a closed seam to several hundred feet. The mineral ized portion of these fractures are very probably derived from the bedded ore deposits and occur either above, below, or opposite the mineralized fracture. The fracture zones are usually filled with mineralized silicious breccia which often appear on the surface as a ledge. Practically all of the zinc and lead mined in north Arkansas has been taken from the fissures and brecciated deposits. Some of the known faults with which fractured lead and zinc deposits are associated are as follows: 1. Rush Creek fault, follows Rush Creek on parts of its course. Throw, 350 feet. 2. Tomahawk, Sections 7 and 8, Township 16 north, Range 16 west. 3. Pilot Mountain, northeast of St. Joe. 4. St. Joe fault, north of and parallel to Mill Creek. Displacement, 250 to 300 feet. 5. Mill Creek fault, south of Mill Creek and nearly parallel to the St. Joe fault, approximately twenty-two miles in length. 6. St. Joe monocline, in Mill Creek valley, north of St. Joe. 7. Hurricane fault, follows a portion of Hurricane branch and Davis Creek. 8. A series of three faults extend from near Jasper in a northeasterly direction to the north-central portion of Township 16 north, Range 20 west. Alteration products.-The alteration products of the region offer nothing new or unusual. They consist chiefly of smithsonite and calamine, but the so-called "tallow clay," described below, is worthy of mention in this connection. Where lead ores prevail there is usually more or less anglesite, cerussite and pyromorphite. *Description of Ores Sphalerite Composition of Ores.-The excellent character of the sphalerite of north Arkansas is worthy of attention. The accompanying analyses show the composition of specimens of clean zincblende, taken at random. Attention is directed to the low iron and high zinc contents. Out of a large number of analyses of sphalerite, the largest amount of iron (FeO3) found was 0.67 per cent. *J. C. Branner, "The Zinc and Lead Deposits of North Arkansas."-Tr. American Institute of Mining and Met. Engineers, Tr. 31 pp. 572-603 (1902). |