Bisbee daily review., 1904-02-21


 surface through four working shafts and several less used openings. The area, more or less thoroughly inter- sected by drifts and crosscuts, covers nearly half square mile, where the extreme vertical range of underground exploration is about $50 feet The workings are practically all in the car boniferous limestone. From $50 to 700 tons of ore are raised per day. chiefly through the Spray, Holbrook and Czar shafts.
 The underground development of the Calumet & Arizona mine is con- fined to the Irish Mag claim. The mine is operated through the Irish Mag shaft, 1900 feet in depth. situ- ated 900 feet south-southeast of the Spray shaft, and about threequarters of a mile in the same direction from Bisbee. The workings are all In the carboniferous limestone. Stoping in this mine began in the autumn of 1902. and about 300 tons of ore were raised per day before the end of the year.
 General Character of Liberalization. The Bisbee quadrangle owes its economic importance exclusively to the occurrence of ores of copper The unimportant deposit of lead carbonate in Hendricks gulch, which was the first discovery in the district, Is still being worked in a small way. and the Easter Sunday mine has supplied the siliceous gol6 ore used in the Copper Queen smelter for converter lining. but these. so far as known. are the only instances in the quadrangle of ores commercially exploited for other metals than copper.
 For district which has produced nearly 00.0o0 900 pounds of copper, the Bisbee quadrangle. in spite of the general baroness of its rocky slopes. exhibits little superficial evidences of it's mineral wealth. The porphyry mass of Sacramento hill. southeast of Bisbee, and the schists that partly in- close it, show considerable alteration and contain abundant disseminated pyrite. which by oxidation imparts a rusty stain to the rocks. but. so far as known. no deposits of value occur wholly within these discolored rocks. Along the Dividend fault in Bisbee outcrop some dark, rusty masses, com posed principally of limonite- Sim liar ferrugincrs lodges occur in Hen dricks' gulch, on Queen hiH. and In the limestone south of Bisbee. Fix perience has shown that such limoniuo croppinss. though rarely exhibiting surerfcisl indications of the presence of copper. are nevertheless freOuently associated with an underlying ore body. They evidently resul: from the oxidation of pyrite. the less soluble iron oxide and some silica remaining near the surface. while such coDDer ore as was originally present has been carried town by percolating solutions and redeDosited al lower levels. These bodies of limonite. when not 500 sili- ceous. are the best surface indications of ore that the district affords Many Of the most important ore bodies. on the other hand. would have remained undiscovered were superficial phe- nomena alone relied upon to suggest exploration.
 Although the rocks of the Quadran- gle are scanned with faults and dikes none of the workable ore bodies occur as lodes or Assure veins. With a few exceptions they are irregular replace ments of limestone Originally py. ritic, and containing probably sub ordinate amounts of chalcopyrite. they owe their present value to secondary ! concentrations effected by processes of sulphide enrichment and of oxida ton.