Bisbee daily review., 1912-10-20

he flldEeS de Nacozafl mine IS To-
 cated in Sonora, 75 miles south ol i Douglas, Ariz. The town of Douglas
 Is on the international boundary, and
 is the place al which the ores from the Bisbee mines are smelted The ] Moctezuma Copper company owns the
 mines at Nacozarl, and the copper | concentrates shipped to the Copper ] Queen smelter. at Douglas make a i good smelling mixture with the Bis i Fee ores. fae Moctezuma Copper company and the Copper Queen | shelter at Douglas, as well as the [ railroad from Nacozari to Douglas, i are owned by the Phelps Dodge com
 pany.
 l The Ore Body
 | The ore deposit occurs in the form i of a large elipse with a major axis | of approximately 2.000 feet. and a
 minor axis of about 500 feet, the ma l joT axis bearing about nine degrees west of north. The whole Of this elipse is more or less mineralized; the surface being principally an iron gossan with some occasional copper stains Below the oxidized zone,
 which is not more than 50 feet deep, the minerals are pyrite and chalco- pyrite, with occasional seams of chal- cocite, the latter being rare. There appears to be no well marked zone ! of temporary enrichment, the oxidlzed gossan over the greater part of the deposit changing suddenly to what is apparently the original unaltered ore. Copper calues Concentrated The copper values are cOncentrat- ed around the perimenter of the el- 1 lipse, and il is principally around this perimeter that the mining Is done. l The ore mined averages a little more than per cent copper. win a small | amount of silver. less than an ounce ! Der ton Some ore of considerably higher grade than this has been | shipped, however. but the above av- | craze is of the mill run. The ore ! is wider near the two ends of the ] ellipse than along the sides, and is | mined in some cases to a width ex- | ceeding 200 feet. The country rock | for the first vertical 500 feet is a volcanic acid breccia. probably rhyo- 1 litic: below this point it is more basic breccia. probably andesitic.
 Contact Marked
 i The contact is plainly marked on ] the surface by bluffs in one place, ] but it is almost impossible to trace | it underground on account of the simi- | lar appearance of the two rocks | when freshly broken. The change in ! formation has no apparent effect or ] the ore: if anything, it is somewhat l richer but more bunchy in the lower | formation. but there has not yet been i enoU Sa work done to verify this state ment The contact between the miueralized rock of the ellipse and | the unmineFalized country rock IS ] plainly marked by a more or less ! definite wall, the rock on both sides 1 of this wall, however, being the same. l The ore is extracted from this wall | toward the center of the ellipse until | it becomes too low grade to mine, although the whole of the interior of the eIlipse would run 1 per cent cop per.
 interesting Study
 This property presents a very in teresting study of the origin of ore
 deposits, and was being examined
 and mapped last summer for the MoC- tezuma Copper company py J. NJ. Bostwell, formerly of the United
 States Geological Survey. There is
 similar deposit at Mount Morgar- Australia, which is also in the form
 of an ellipse, though less than had the size of the one at Nacozari.
 believe it is worked for the gold val ues, and the whole of the ellipse is more or less workable. At the Brad en copper mine, Chile, there is an ore body of the same shape, but there the ore occurs along a contact of a volcanic rock which is intrusive in an older rock and different while at Nacozari the country rock and the interior of the ellipse are apparently the same Railroad Direct From chutes
 IShe mine is operated by two B. compartment shafts, situated onp at each end of the eliipse, and an adit tunnel about mile long. which taps the deposit at point a bout GOO feet below the collar of the shafts. This adit is large enough to allow narrow gauge, 25-ton railroad cars 10 load from the mine ehutes, and it Is chif- Iy due to this cheap handling of the ore that the enterprise fas become so commercially successful The railroad runs to the top of the bins above the eoncentratoF. which it sit uated on the NacozaFi railroad at the town of Nacozari. about five miles from the mine From here the con centrates are shipped to the smelter at Douglas. Ariz. The daily output of ore is between 1,J00 and 2,0O0 tons.
 Levels
 The levels in the mine are 100 feet apart; and the general plan Is to use every alternate level as a stoping base, the intermediate iey-
 els being used for development, ven tilation and ihe distribution of waste to the stopes that are being filled. At the present time practically all the ore is being mined above the
 adit level, which Is known as the
 700" and at the present rate of out put there should be. on a rough es- timation, approximately an ore sup ply of at least 10 or 12 years above this level. The shaft at the north
 end has heen et1nk fO fhe 1 110 foot