Arizona republican., 1917-06-17

The principal ore zones of the Old Dominion mine occur in a fault vein, having a northeast southwest strike. The hanging wall is main K limestone and quartzite; the footwan of ;, limestone, qlaltzite and diabase. The ores favor the sedimentalies for deposits and oc- cur, principally ill lenses along certain beds of the limestones and i'll the quartzite, and some very large lenses have been developed The oxidized ores are mainly cuprite, associated with little malachite and chrysocola in a gangue of iron oxides and quartz.
 about $50 feet as chalcocite, with gangue of pyrte and quartz, the lower workings also showing chalcopyrite, bornite and chalcocite. Some of the ores are highly sliceous, requir- ing heavy lime and iron fluxes in smelting. Large sulphide shoots appear on the 14th level and below, and have improved most wonder fully in the deeper workings. The ore bodies to the west show very good values ill copper.
 The principal working entry of the Old Do- minion mines is known as Shaft A, and is To- cated on the east side of Pinal creek 1t is down to depth of 400 feet and has been made modern in construction ill all respects, with four hOisting compartments and pipe and ladder-way From the A shaft numerous levels have been run, the deepest being on the 18th.
 Auxiliary to A shaft are other shafts known as B, bottomed at the 12th level, at the 14th level, the Kingdom shaft at the 14th and the Gray at the 12th level This is also the Tran sit development shaft and number of small shafts and adits to open up the property The rl- 6oInc cal and power departments is of the best modern type and make and mining methods have been well adapted to conditions. In the ore bodies on the east side of the mine stoping is done by the Till system of cut and fiji on a 45 per cent incline and very little timbering is necessary, for the formation is solid. West of the shaft the ground IS wet and heavy and , square sets and filling are used
 All ore and waste are hoisted in skips From the skip dump, which is at A shaft, the ore falls into pocket, as does also the custom ore which is discharged by belt conveyor, fed from the unloading bins at the railroad. Out of this pocket 1t discharges over an apron feeder to the 26-inch belt conveyor that feeds the mill. From there it is delivered over 24-inch convcyor to the sampling mill
 
 run ore, fluxes for the shelter, have been erected. There are five furnaces, one 231x44 and four 19SX44.
 Some of the new construction work recently completed includes a crusher plant and sanl- pie mill, capable of handling 120 tons per hour and which was completed toward the end of 1913, and new concentrator, capable of hand . ling TOO tons per "A hours, completed in Sep tcmbcr 1914.
 Included ill the mill plant there is a 30O-ton mineral separation Notation machine for treating the shines in the ore. Total recovery of copper in the new mill shows great i'm provement over the old one An Oliver Filter has been installed recently to deWatcr the Notation cOncentr; ted.
 In the smelting department no new equip ment has been added ill the last two years. A converter shell, put on the stand in July, 1913, has handled the entire copper production for the last 31 months and only recently came Off the stand It produced, without any reclining being done, over 36,000 tons of copper
 In the mine during 1915 a new system of hoisting waste by skips was installed, which is working very satisfactorily, and also two big additional skip pockets were constructed on the 10th level. The 16th level is the pres ent lowest operating level. Three 1,200-gallon Aldrich quintuplex pumps were installed on the 18th level in July, 1914, but the flow of water to this level has been very heavy and