A former Mn occurrence/mine located on 5 claims in sec. 8, T7S, R16E, G&SRM, on the N side of Putnam Wash in Camp Grant Wash, about 1 mile west of its junction with the San Pedro River, about 10 miles NW of Mammoth,and about 13 miles from Winkleman at 2,300 feet of altitude, on private land. Discovered in 1916 by Tarr and Harper. Owned by the Arizona Rare Metals Co. (1917); and, R. D. Harper (1918- ). Produced 1917-1954. Operated by Mr. Grant Godfrey (Lessee), and Mr. M.N. West (Sublessee). Owned by the State of Arizona.

The manganese deposits are contained in fissure veins which cut both the older sedimentary rocks and the younger sands and conglomerate. The fissure in the older rocks trends N45W & dips 45NE & lies in the bedding or cuts the beds at an acute angle. The fissure in the gravel beds strikes about N10W & is nearly vertical. The deposits pinch and swell along strike. The vein is 1,500 feet or more long and is a few inches to 4 feet wide. In places there are 2 ore-bearing streaks a few feet apart, separated by brecciated material of the fault zone. The most important Mn deposits are along a fracture zone in Mescal Limestone and Quartzite. Some Mn is found in fanglomerates which overlie older sedimentary rocks. Most mineralized zones follow bedding planes, which strike N20 TO 45W and dip 25 to 45NE.

The manganese oxides have been deposited in the open spaces of the fissure and have also replaced the crushed wall rocks to some extent. Iron oxides occur sparsely but they are abundant where diabase is the enclosing rock of the fissure and are intimately mixed with the manganese oxides. Calcite is an abundant mineral of the ore, and is of secondary origin.

Local rocks comprise beachlands that are composed of slightly indurated and poorly stratified sand, pebbles & angular rock fragments. These sediments are at least 200 feet thick and may be much thicker. The old sedimentary rocks consist of limestone at the base, intruded by a diabase sill, overlain by conglomerate, which grades into gritstone & hard white quartzite. The formations strike NW & dip NE. They are flanked on the east by flat-lying sand & conglomerate beds and west of the mine they overlie granite of Precambrian age.

Workings include surface and underground openings comprised of an 80 foot (24.38 meters) deep vertical shaft on the north side of the wash, plus about 275 feet of tunnels and a few shallow holes on the south side of the wash, a 50 foot inclined shaft, 3 adits, one stope 3 to 6 feet wide and 450 feet long and one open cut 45 by 65 feet.

Production included 407 tons which were 40% Mn (1917), and 2,825 tons which were 19.8% Mn. In addition, several hundred tons of less than 15% ore and 5 carloads were shipped.

Assay data: Analysis of a grab sample of ore showed: 11.5% Mn, 4.9% Fe, 0.01% Pb, 0.02% Zn, and 0.05% Cu.

Concentration of ore by gravity methods alone is impractical because of the interlocking nature of the manganese and gangue.

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Link to USGS MRDS:	10088604

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References