Mossback Mine, Gold Road Mining District, Oatman Mining District, Black Mountains, Mohave County, Arizona, USAi

Regional Level Types
Mossback Mine	Mine
Gold Road Mining District	Mining District (Inactive)
Oatman Mining District	Mining District
Black Mountains	Mountain Range
Mohave County	County
Arizona	State
USA	Country

MOSS BACK MINE.

Location and history. The Moss Back mine is situated 3 miles by trail northwest of Gold Road, in open country near the foot of the range, at about 2,400 feet elevation. It is near the upper edge of a bluff about 80 feet high overlooking a wash on the northeast. The property comprises three claims. It is reached by wagon from Gold Road in a distance of 7 or 8 miles by descending Silver Creek nearly to the Moss mine road forks.

The deposit was first located about 1863 by the Barry Mining Company as the Blanco ledge, so-called from the whiteness of its croppings and ore. It was relocated in 1864 and thereafter abandoned and finally it was again relocated in 1901 by Charles H. Burlock and wife, of San Diego, Cal., who still own a four-fifths interest in it, the remaining fifth being owned by the Moss Back Mining Company, of Los Angeles.

There has been no production, but about 900 tons of what is said to be good milling ore lies on the dump.

Development. The mine is developed principally by a main shaft, drifts, and crosscuts to a depth of 330 feet. The workings also include a crosscut tunnel 150 feet in length on the southwest. The mine is said to produce a plentiful supply of water for ordinary milling purposes. The water rises within 170 feet of the surface. The mine is now dismantled of its hoist and surface equipments and the ladders have been drawn from the shaft. Besides the water produced by the mine a never-failing source of supply is a constant spring located at the foot of the range about a mile northwest of the mine and about 400 feet above it, with which there are pipe-line connections.

Geology. The Moss Back deposit is geologically and mineralogically very similar to that of the Pasadena mine. The country rock is the green chloritic andesite; it is locally pyritic and is intruded by rhyolite dikes and masses and by fresh black basalt or basaltic andesite. The structure or sheeting trends about N. 80° E. The rhyolite is also in part mineralized and is reported to assay from $2 to $3 a ton all over the surface; it contains veins or reefs of silicified rock, and is cut by diabasic basalt dikes. In the small hill east of the mine it contains a 1 to 2 inch rich gold-bearing
stringer with much hematite.

Veins and ore. The Moss Back vein or lode dips about 80° SW and has a known extent of nearly half a mile; the width at the surface is at least 23 feet, and it is said to widen to 40 feet in the bottom of the mine. The vein consists essentially of a mixture of gold-bearing, medium to coarsely crystalline calcite, with a small percentage of fine-grained silica or quartz and probably adularia, which has seemingly replaced calcite. It also contains a considerable amount of the greenish mineralized country rock andesite, which occurs in streaks or small bodies and carries low-grade values. The croppings are more or less silicified portions of the vein above described, for the most part stained by iron and manganese oxides, and contain in places masses or clusters of quartz blades representing the replacement of calcite by the quartz along its crystal faces and cleavage planes. There is but a small amount of gouge, but the wall rock next the vein is usually sheared, silicified, and veined by quartz or calcite.

The principal portion of the vein or main ore shoot, the part best defined at the surface, has a width of 12 to 15 feet and contains from 4 to 6 inches of gouge material consisting of sheared and crushed rock, calcite, and quartz on its foot-wall side.

The ore almost everywhere contains disseminated minute blackish specks of hematite, and these, particularly in the spar, are reported to carry the gold in very finely divided particles. The values rise with increase in the amount of silica in the spar, the best ore being in association with the silica. Some small pockets of yellowish-brown "sugar quartz," which consists principally of colored spar, with an admixture of silica and limonite, are said to have contained up to $2,000 in gold to the ton.

A 17-foot crosscut from the main shaft to the southwest at a depth of 200 feet below the surface, which has not yet reached the hanging wall, is said to show good ore throughout its extent, running from $6 to $9 to the ton. In the shallow workings on the southeast a 10-foot width of the vein, is reported to average $31 in gold to the ton.