Bisbee daily review., 1904-03-05

| Below is presented the fourth ano concluding paper, by F. l. Ransome on the geology and copper deposits of
 Bisbee. Arizona. the other three in
 stallments of which article have ap-
 peared each week in previous issues | of the Review:
 In general, the zone in which the metamorphic silicates are developed is that in which most of the ore bodies are found. In the western part of the Copper Queen mine. however, ex- | tensive ore bodies occur in limestone that is perhaps outside of this zone. In other words, the deposition of metallic sulphides appears to have had a wider range, and to have ex. tended further from the porphyry into the Assured limestone than did the formation of the metamorphic sili- cates
 That the original ore deposition was genetically connected with the intru- sion of the granite-porphyry of Sacra- mento hill is reasonably certain. The other factors, which by their fortunate conjunction determined the original I mineralization of this part of the dis trict, were the contact of this consi6- erable mass of porhyry with lines tones, the occurrence of the Dividend fault and other less important frac- lures, and the attitude of the lime stone beds with reference 10 the DOT phyry and to these faults. The hy- pothesis is advanced that the cepcsi- tion of the cupriferous pyrite and the metamorphism of the limestone schist and porphyry was effected by the mingling of solutions from different sources in the vicinity of the Dividend fault and of the Sacramento hill DOT phyry. The principal function of the porphyry is believed to have consisted in the supply of heat to such solutions as rose from great depth through the fault Assures and in determining the locus of chemical activity that result
 
 The source of the ore materials is not known. They may have risen through the Dividend fault from depths far below the bottom of the cyncline Of paleozoic rocks. They may have been collected by solutions moving through one or more of the paleozoic limestones cn their way cown to the locus of deposition. Lastly, they may have been derived from both sources. Few, if any, of the ore bodies now known and worked in the Bisbee dis trict were formed directly by the original naturalization just discussed. That process resulted, so far as under ground workings show, mainly in the formation of bodies of supriferous py- rites passing peripherally into meta morphosed and pyritized limestone. These bodies contained originally too little copper to be classeG as ore, as that term is defined by present eco homie conditions of woring. Further concentration was necessary, and the profitable ores of today have been de rived from these pyritic masses by secondary processes involving general | oxidiZation, with all of its attendant 1 chemical phenomena, transfer of ma ] terial and the local enrichment of cer-
 tain portions of the sulphide masses
 by the formation of chalcocite, and, in some cases, of chalcopyrite.
 The lower limit of oxidization of the
 BiSbee ores is very irregular and is apparently uncontrolled by any con
 stant ground-water level. In the Cal
 umet & Arizona mine oxidized ores occur at a depth of 1000 feet. while
 residual masses of sulphide ore occurs
 in the adjoining Copper Queen mines
 within 150 feet of the surface Masses
 of lean pyrite are sometimes com ] pletely enclosed in an envelope oi !, high-grade chalcocite and oxidizet ores.
 l ". Future of the District-Al | though more or less naturalization oc
 CUTS at many points in the Mule noun tains, there is little to indicate that
 any deposits of copper ore will evel
 be found in the Bisbee quadrangle ap | preaching in importance those already
 known and probably awaiting 6iscov
 cry in the faulted limestone synclint
 about Sacramento hill. For nor,
 than twenty years the Copper Queer
 mine has produced an average exceed ] ing 16,000,00 pounds of copper annu ally. Recently, the Calumet & Ari
 zona company has begun energeti, operations in ground almost surround
 ed by the property of the Copper Queen Consolidated Mining company
 Not only is there sufficient ore knowr
 in these mines to keep them in oper l ation for many years to come, but there Is no clear evidence that ths I h <<f Al A