Three-R Mine (3R Mine), Three-R Mine group, Three-R Canyon, Palmetto District, Patagonia Mts, Santa Cruz Co., Arizona, USA
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A copper mine located on 30 or more claims on the eastern border of the district, 4½ miles south of Patagonia. It is in the upper west slope of the Patagonia Mountains near the axis of the range, mostly between elevations of 5,100 and 5,500 feet. Discovered in 1897. Bonded to W.R. Green, of Cananea circa 1899-1907; later the Lewisohn people, through H.S. McKay, took an option on it for about 4 months only; and, owned by the Three R Syndicate (circa 1909); R.R. Richardson was a leading owner in 1911; by April, 1912, it was bonded to N.L. Amster of Boston, MA.
This mine is in the upfaulted block of the Patagonia Mountains. The country rock is mainly the granite porphyry. It is composed of quartz and orthoclase in large aggregates with rarely a little biotite. It is much weathered, altered, pyritic, and iron-stained, and is vertically sliced by two systems of sheeting, of which the dominant system trends about north-south, parallel with the Colossus lode, and the other about N.75ºE. Mineralized shear zones occur in both systems, some of them being marked by ledges with enormous croppings, such as that of the Blue Rock No. 8, southeast of the Three R Mine, belonging to the east-west system. The rock, especially in the vicinity of the north-south shear zones, has also been pressed and sheared to a high degree, so that it weathers like a schist, which it locally resembles. It is cut by dikes of rhyolite and a younger granite porphyry, but these rocks seem to be only sparingly present.
Mineralization is ore deposits that occur in a north-south shear zone about parallel with the axis of the range, traversing the granite porphyry country rock, which is heavily impregnated with pyrite, apparently cupriferous, and a little chalcopyrite. Along the shear zones there is a concentration of these minerals, forming crude stockworks and veins. Alum and copper sulphates coat the workings.
At and in the mine the shear zone has a width of 40 to 100 feet or more, and is variously traversed by parallel stringers, seams, and bands of ferruginous rock or hematite. One of these bands is about 1 foot (30 cm) in width, is partly honeycombed, and in part has a laminated or platy structure, being apparently pseudomorphous after calcite or some othe spar mineral. This band is said to carry some copper and gold, and father up the mountain side it contains lead minerals as well.
The Colossus tunnel, driven in the shear zone, largely follows a slip or fault plane, which dips 75ºW., and is associated with a ½ to 1½ inch (1.25 to 3.75 cm) band of hematite or reddish-brown ferruginous rock, on the footwall side of which occurs from 1 to 3 feet of crushed and partly mineralized reddish-brown, iron-stained granite porphyry. The zone also contains seams, stringers, veins, and lenses of rich copper ore, consisting of malachite and chalcopyrite with pyrite, bornite, and chalcocite, of which the largest observed is a band about 2 inches (5 cm) wide, composed of pure chalcocite, enclosed in slickensided porphyry and whitish gouge, showing that more or less profound movement has taken place sinc ethe chalcocite was deposited. Native copper occurs, apparently derived from chalcocite.
As a rule the sulphides begin at or very near the surface, about the only exception being the Mayflower opening (tunnel), at the top of the hill, where, owing to leaching, much carbonate is encountered.
Workings comprised several thousand feet of work consisting of tunnels and drifts distributed through a vertical range of about 400 feet. In 1909 there were three tunnels, located, respectively, at elevations of about 5,200, 5,300, and 5,500 feet, with lengths of about 200 to 300 feet. The Colossus, or main tunnel working, contained about 70 feet of crosscut to the east, and as much more to the west, and a 70 foot deep winze. There was also a 375 foot deep, double-compartment shaft. A new 600 foot lower tunnel was driven circa 1915. It contains 500 feet of drift on the vein and a 90 foot winze with drifts at 60 feet below the tunnel level.
13 entries listed. 11 valid minerals.
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