Bisbee daily review., 1907-03-17
G|LA RIVER ALUM IN MARKETABLE
 QUANTITIES.
Value of Immense Deposits Is Dependent on Amount of Im- puritieS and Skill Used in Getting It Out.

Deposits of alum that present many
 unique characteristics occupy a small
 arid region in Grant county N. NJ on
 both sides of the Giia River. These
 deposits, which have been studied and described by MT. c. w. Hayes of the
 United States Geological Survey. lie about twenty-seven miles due north ot
 Silver City and are at present accessi
 ble from that point by a wagon road
 which reaches the Gila River at Lyons Hot Springs about six miles above and thence follows the river down to the mouth of Alum Creek.
 The alum deposits occupy a nearly circular depression below the general level of the volcanic plateau. The rocks of this topographic depression are andesitic volcanic breccias. They are the alum rock. The main mass of this alum rock occupies a nearly cir cular area. lying for the most part south of Gila River and west of Alum Creek. About the margins Of this main mass are smaller areas occupied by the alum rock. the largest being north nf the river. Several, small areas are found in the upper basin of Alum Creek. The relations of the alum rock 10 the adjacent basalt indicate clearly that the alum rock has broken through the basalt in the form of an igneous intrusion, probably with in- tense explosive violence. In eSery case where the contact was well ex- posed it was either vertical or at a high angle and the alum rock contain ed fragments of the basalt.
 The most striking peculiarity of the alum rock is its extreme alteration. Careful search failed to reveal at any point within the Alum Creek basin a trace Of the unaltered breccia for de- termination of it's original character. Where exposed to teaching as in the upper parts of pinnacles and cliffs the rock is always porous, giving a hollow sound under the hammer. It is evi- dent that a considerable part of it's substance has been removed in solu- ton.
 Two forms of incrustations having entirely different chemical compost tion are common in association with the alum rock wherever the conditions are favorable for their accumulation. Upon the sides of the cliffs are exten- sive deposits of material evidently leached out Of the adjacent rock and deposited from solution. These in- crustationg vary in thickness from a few inches to three or four feet. The outer surface has a fluted appearance resembling some stalactitic cave de- posits. It is generally yellowish white powder. This incrustation consists of the hydrate sulphate of aluminium known as alunogen. The white pow dery material is very pure and has practically the theoretical composition of alunogen, while the outer crust contains a slight amount of impurities and less than the theoretical amount of water.
 The second form of incrustation Is most abundant OF the walls of the tunnels which have been driven into the alum rock. It consists of halotri- chite, silky fibrous mineral closely resembling asbestos in appearance. It has a very pale greenish color and a strongly astringent taste. The outer exposed surface of the incrustation has generally lost its fibrous structure, be coming compact and assuming vel Jewish color. Although the incrusta- ton may be several inches thick. the individual fibers are rarely more than a third or half of an inch in lengtn, the crust being made up of successive layers of short crystals. Each layer probably represents the growth of a single season during which the supply of percolating water was relatively abundant. The layers of crystals are sometimes separated by a very thin finn of the rock which has been split off by the growth of subsequent layer of crystals.
 The alunogen of the first incrusta- ton is the sulphate of alumina and is free from iron except as a minor impurity. the halotrichite of the sec ond is the double sulpifate of alumina and iron.
 The value of the deposits will de- pend on the utilization of the soluble suIphates which they contain. The present surface accumulations of alu- nogen, while probably amounting to many hundreds or more probably thousands of tons. represent but an insignificant quantity compared with the sulphates still in the rock. wher- ever observed the rock is highly po- rous, and the extent of its porosity represents the amount of material re- moved. In the higher and more ex- posed lodges the rock is thoroughly leached and will yield nothing more, At lower levels the rock still contains a part of its soluble constituents which are coming to the surface by the capil- lary circulation of surface waters.
 Success in the development of this deposit will depend largely upon the skill with which the problem Is hand led. That there exists here an almost unlimited supply of aluminium sui plate appears, however, certain and In view of.the rapidly growing demand for this substance in the arts. and in sanitary engineering and as source of tbe metal aluminium. there is iit- tie question that the supply win in'