The copper era., 1904-02-11
CLIFTON-MORENCI QUADRANGLE
Written for The Mining World by Frank II Probsrt.

Written for The Mining World by
 Frank II Probert
 The Clifton-Moreuci copper di-tric i- situated in Graham county, Arizona few miles wc-t Of the New Mexic, line. and about sixty miles north O the Southern Pacific railroad. Tn, earliest records of mining in this sec tion date back to the seventies, since which time the district has grown very rapidly, until now it i7 producing over % tons of metallic copper daily. The total output Of Arizona for the year 1902 was approximately l20. O1Q.- 900 pouud-, vi winch this section pro duced over 5O.OOO,OOO pounds. The output for 1903 will, in all probability, exceed ibis figure, and in fe" years it will rank second 10 none of the great copper districts Of Arizona. or the three large companies operating in the field, the Arizona Copper com pany alone. during the year ending September go, 1902 treated in their mills 195 el9 tons Of ore, and conten- tratc. The ore and concentrates F.Ntl'ih diIbAiI -il At D 'tD i.'li7s " llil the teaching pldnt handled 35.72l tons Of tailing- The average yield of all the copper ores treated by this com pany was 3.37 per cent. Owing to the decrease in the percentage yield of inc ore now being mined, more at- tcntiou will be given in the future to increased efficiency in operation and lower cost of production than Co mak- ing moro copper. The enormous ore bodies known to exist assure long life of the mines, and the great ad- vanccs being now made in the per fecting Of suitable concentrating ap- plianccs, makes it possible to treat q lower grade of orc at q profit. lm- provemcnts in concentration, and in the handling of material will make it possible to work ores 2t per cent. yield in the near future.
 Clifton. q town of some 5,OO0 in- habitants, is situated on the San Fran cisco river, srveu,y-eight miles from Lord9burg, New Mexico, where the Arizona G New Mexico railroad joins the main line of the Southern Pacific It has an elevation of 3,i6j feet. Met calf is situated on Chase creek, six miles north of Clifton, while Morcnci i5 four mics to the northwest. Mo rcnci is the home of the Detroit Cop per company-phelps, DOGge X Co.,, Of Now York. IL has q population of about 4,0oO. Both Mctvau and Mo- rcuci are connected bv narrow gauge lines with the Arizona S, New Mexico railroad.
 GEOLOGY.
 Tho oldest rock exposed in the ir- regular complex of mountains is gran ite of prc-Cambrian age, upon which rests series of scdimentarics of the Cambrian, Devouian and Carbouiicrous ages, fully LOGO feet thick. Overly ing the granite is a bed of quartzite 200 feet thick, then comes an impure limestone, followed by a band of De- vonian shale about leo feet thick, and lastly the purcr limestones of the lower carbouiferous. Subsequent to the quicscent period of sedimentation. violent volcanic disturbances took place, intruding misses Of porphyry in the form of dikcs through the igneous and aqueous rocks alike. Fol lowing this eruption, violent fractur- ings of the whole series of rocks took place. resulting in a complicated ays- tenn of faults
 The porphyry vary considerably in their texture and general character istics, acid and basic porphyrie- being represented. This may b. due to magnetic segregation. d. they are of the same geologic age. At Morenci the dikes consist of fine grained diorite porphyry. whereas in the Met calf mines a decided quart crystals is found This fact also has peculiar bearing on the type of ore deposit found. The more acid granite DOT phyries generally contain small high grade ore shoots, while in the softer varieties. the finely disseminated black sulphides are found.
 ORE DEPOSITS.
 The intrusion of the porphyries is accountable for the copper deposits Of this district. Two distinct types of orc deposits are recognizable, Assure veins and those due to contact meta mOrphism. There are true Assure veins as, Q. E., the Humboldt, and fault Assures such as the Coronado. The outcrops Of these veins have in most cases been completely leached, there being nothing but little car bonate stain, or else limonite and .iliciied porphyry. Indeed, 10 the