Show possibilities bi ai ti es of the alo ajo mining mi ning district di ct the ajo copper district lies in southwest arizona about thirty miles north ol of f the mexican line miles west of tucson and forty three miles south of gila bend the nearest railroad point the little ajo mountains rise a few hundred feet above the desert valleys and the camp itself lies in a small basin on the east side of the range separated from the open desert by the low hills its elevation above sea level is about 1900 feet in the center of the basin the brilliantly stained rocks of copper mountain rise feet above the village the scanty supply of water is obtained from the wells in the desert and from prospect pits in the camp the nearest abundant source of water is the gila river fifty miles north next to santa rita N M the ajo district is said to be the first southwest copper district to be worked by americans a high grade material having been hauled out in the early sixties A good many stock mining geologist warren ariz paper presented at the salt lake meeting of the A 1 I M X E BY IRA A JORALEMON companies at one time or another have been organized on the strength of surface showings in the fall of 1911 the calumet arizona took an option on all available stock of the new cornelia copper company one of the recognized companies that had attempted to work the district the C A started prospecting by diamond drilling following this with test pitting and with drifting in the sulphide zone the work resul resulted teI in the outlining under the iron and copper stained outcrop of a low grade copper ore covering an area of about fifty five acres and reaching a known maximum depth of over feet below the surface following this development james phillips utley wedge and others under the name of the ajo copper company took an option on the rendell ore reduction company and the united states smelting smelling Sm elting refining mining company took an option on the chlde group of claims between the new cornelia and the rendell properties the united states company gave up its option after sinking a fe few v churn drill holes the phillips interests however still hold their property but without doing any development work proving the ore body to develop the new cornelia property the ground considered as probably ore bear ing was coordinated co with east west and north south lines at foot intervals and drill holes were sunk at the intersections the actual drilling was conducted by the E J longyear company of minneapolis and the sampling was done under the direction of the calumet arizona representatives after six months of drilling test pitting was begun for the sake of checking tile the drilling results the pits were about feet in size sunk with windlass and hand drills mexican and papago indian miners being employed the work was done on contract and after practice the men became so efficient that up to a depth of five feet test pitting was cheaper than diamond drilling during the last year of devel development test pits were sunk fifty feet deep on the coordinate points in advance of the adril ing in order both to expedite the work and to decrease the drilling cost every tenth bucket hoisted from each hole was taken for a sample and large samples were thus obtained for every round shot then after the pit was completed it was re sampled in five foot sections by cutting a rectangular vertical groove three inches deep by six inches wide so as to give about a pound sample for each five foot section these channel samples averaged about 15 per cent lower than the bucket samples and were taken for the final samples of the pit in the sulphide ore the pits encountered water which made sinking so slow that only a few hundred feet was done in the sulphide zone however to check more thoroughly the drilling results in the sulphide and prove a constant grade of ore between drill holes drifts were run on coordinate lines from the of two of the deepest test pits and raises were put up from these drifts to check the drill holes for the sake of giving accurate samples the material broken in each round was hoisted separately dumped on an iron plate and every tenth taken out for the large samp sample e to be cut down later up to september 1913 when development work was stopped 84 diamond drill holes had been bored varying in depth from to 1000 feet and giving a total footage of of these nineteen were stopped in ore in all seventy seven test pits were sunk with a total footage of of this feet was in carbonate ore and in sulphide 1059 feet of the test pit ting checked drill holes in carbonate ore feet checked drill holes in sulphide and 2721 was done in advance of drilling the drifting ra ing in the sulphide ore amounted to 1513 feet and the combined sinking and raising on drill holes in sulphide ore was feet the sinking drifting and raising checked the drilling accurately acura tely the channel samples of the test pits in carbonate averaged per cent lower than the corresponding diamond drill samples the test pits and raises in sulphide averaged per cent lower than the diamond drill samples and the drifts in sulphide averaged per cent higher than the assay value of the blocks through which they were run as indicated b by y the drill holes at the corners of the blocks in calculating the ore drill samples f were used wherever drilling was done ana channel samples of test pits were used where sinking was done in advance of drill ing the estimate of the ore developed is as follows copper ore estimate tons PO PC carbonate Sup sulphide hide F total available by steam shovel carbonate sulphide 20 total not available by steam shovel sulphide rock which must be removed to make steam shovel tonnage available rock in carbonate zone rock in sulphide zone total rock the gold and silver content is low generally amounting to less than 15 cents per ton in computing the tonnage no material running under I 1 per cent in copper was included the estimate of ore available steam shoveling depends on the assumed maximum grade of track in approaches and pits and on amount of lean rock in the sides and bottom of the pit which it will pay to remove in order to get access to the ore it is likely that the proportion demov removed ed by steam shovel will be greater than that indicated in the table not No tonly only will there be no stripping expense but the absence of overburden precludes the possibility or of lowering grades by the admixture of barren material both tonnage and content of copper therefore should come out closely to the estimate three problems will arise in connection with the exploitation of the new cornelia copper property these are the questions of treatment water supply and railroad communication muni cation the question question of treatment has been pretty well worked out As for water two deep wells were drilled in the large valley northeast of ajo ana alia water was in both at a depth ranging from to feet by means of a boiler plant and compressor the water was raised from one of these drill holes with an air lift having a capacity of about 9 gallons allons per minute pumping at this rate did not exhaust the water in two weeks in view of such lucli a flow from an 8 inch drill hole it seems reasonably sure that a shaft with a little drifting will furnish an ample supply and such a shaft has been started As for the rai railroad road preliminary surveys have been made both from gila bend on oil the southern pacific and from tucson the junction point of the southern pacific and the el paso southwestern systems the respective distances are 44 and miles both lines would lead through a gently sloping desert country and should be constructed ted at a cost of less than per mile the route has not yet been selected the ore body already developed will supply a ton mill for over twenty six years indications are that the life of the mine wh be greatly lengthened by the development of a large tonnage of deep ore along the fracture zone in the center of the ore body for the next quarter of a century the ajo will beane be one of 0 the greatest copper districts of the southwest |