1()2 MONTANA: INDISTKIAL KKSOURCES 



ICELAND SFAK 



Uses — For (iptical purposes, especially in insirunu'iits fur polariziu.n li,t;lit. 

 Occurreiu-e — In Sweet Grass County. 



KAOLIN 



Uses — Extensively used in niauufacture of porci'lain. 

 Ooeiirrenoe — Reported found in Fallon county. 



LIMESTONE 



Uses — The most generally useful sedimentary rock. As Imildinsj; stones. As 

 practically the only source of lime and indispensable in cement manufacture. As 

 fluxing material in smelting industry. A pure limestone is extensively used in 

 sugar-refining. A fine, compact, homogeneous limestone, which may be either 

 a pure carbonate of lime or dolomitic. is used as lithographic stone. It is found, 

 of a quality suitable for lithographic work, at only a few localities. Two 

 classes are known to the trade, the "blue"' or hard stone, adapted to engraving and 

 the better grade of fine-line printing: and the "yellow" or soft stone, which is 

 rated as somewhat inferior. 



There are many different kinds of limestone. The kind most suitable for one 

 industry may be the least adapted to another industry. For Portland cement an 

 argillaceous (clay) limestone which contains lime, silica, and alumina, in such 

 proportions that in the finished cement the ratio of lime to the silica, alumina 

 and iron oxide taken together shall be not less than l.G to 1. or more than 2.3 to 1, 

 is most desired. For every ton of limestone u.sed in manufacturing in<liistries, 

 three tons are used as furnace flux. 



Ot't'urrence — This rock is abundant in the mountainous parts of the state. 

 Its principal use up to the present has been as a furnace flux in the smelters 

 and in the manufacture of lime. The increased use of stucco for plaster has re- 

 duced the market for lime and kilns in a number of districts are idle. Accord- 

 ing to Rowe there are many deposits of good limestone in the state. l>ut most 

 of them are too remote from the railro.-ids to permit profitabh' operation. 



Rowi> reports limestone in Lewis and ("lark. P(nvell. Cascade. Fergus. Cjwbon. 

 Beaverhead. Silver Bow. .Tefferson, Sweet Crass. Gallatin. I*:irk and Deer Lodge 

 counties. 



ivncA 



Uses — Indispensable in electrical industry as insulating material, in wireless 

 apparatus, in magnetos. Also used in stove fronts, chimneys and lamp shades and 

 sounding lioxes of phonographs. Asserted the enormous expansion of the electrical 

 industry due in l;irge part to the iuii(iue properties of mica. To be of \ahie as 

 sheet deposits must yield a rectangle at least IV. by 2 inches, which nuist 

 split readily, be free from cracks, corrugations, etc. Tlie only connnercially valu- 

 able varieties in the United States are ma.scovite (common) and biotite (black 

 mica ) . 



Orcurrence — U. S. G. S. quotes report of prospect eight miles southeast of 

 Dillon. Beaverhead county, that is said to have yielded plates S14 l\v 18% inches. 

 Another prospect was n^ported near Barker. Cascade county, in a bed four feet 

 thick. Also reported on Granite Creek, between Virginia City and Sheridan, 

 Madison county. Mica said to be of good quality, clear and well grained. Also 

 reported on proju-rty of Zonolite Alining Company, near Libby. Lincoln lount.v. 



NITRATE 



I'ses — Chiefly as fertilizer and in manufacture of explosives. 



Oc'curreni'C' — V. S. G. S. rei>orts (Uposit of niter along face of cliffs of black 

 limestone, on Camp Creek, three and one-half miles northeast of ^Melrose. ^ladison 

 county. No explorations to determine if potash .and scnla nitrates are included in 



