160 MONTANA: INDUSTRIAL RESOURCES 



should contain 60 to 70 por cent of silica and the iron oxide and alumina together 

 .slidiild not exceed one-half the pex'centage of silica. 



Occurrence — The only general survey of Montana's clay resources was made 

 liy Rowe. He reports deposits of brick clay at several places in Missoula, Sanders, 

 Flathead and Ravalli counties, in Lewis and Clark. Silver Bow. Powell, Cascade, 

 Rosebud, Yellowstone, Gallatin. Phillips, Valley, Park. Blaine. Hill, Beaverhead. 

 Carbon, Granite and Fergus. The U. S. G. S. reports l>rick clay in Sheridan 

 county. 



Rowe reports deposits of fire clay in Powell and Jefferson and at two places 

 each in Lewis and Clark. Cascade and Flathead counties. 



Potterj' clay is reported in Powell. Missoula and Gallatin comities, at several 

 places in Sanders. Flathead and Ravalli counties, beneath coal veins in Fergus 

 county, and possibly exists In Sheridan and Carbon counties- The clay in Carbon 

 county may contain too much pyrites for pottery purposes, and the color of the 

 Sheridan county clay may be objectionable. 



The T'. S. G. S. reports bed of clay between Plentywood and Redstone. Sheri- 

 dan county, known extent of which is 18 miles east and west and eight miles north 

 and south. Bed from three to eight feet thick. U. S. Bureau of Standards tested 

 representative samples and reports the "clay appears to be a promising 

 one for the manufacture of common and face brick and possibly drain tile and 

 fireproofing. The buff color developed by burning would not permit its use 

 in the manufacture of whiteware pottery. However, the clay has properties 

 similar to those used in the manufacture of stoneware". The U. S. G. S. points 

 out that the presence in the area of lignite will aid greatly in the exploitation 

 of the bed and the manufacture of clay products and the report concludes: 

 '"Though the local demand for the clay products may not be great, the association 

 of lignite and clay, together with the advantages of location and transportation, 

 may make the deposit valuable to the prospective manufacturer". 



CORUNDUM (Indushial) 



Uses — As an abrasive. Molded into wheels, whetstones, slips, hones and 

 oil stones. Also used in powder of various degrees of fineness and made into 

 abrading papers for polishing, stone and gem cutting and polishing, dental work, 

 glass frosting and etching, and wood-working. In the gem form as a sapphire 

 used for bearings in many delicate precision instruments, such as watches and 

 various meters. 



Occurrence — Reported by U. S. G. S. on headwaters of Elk CreeK, '23 miles 

 south of Belgrade. Gallatin coiinty. Corundinn-bearing rock eight to ten feet 

 in width. Corundum crystals vary from fraction of an inch up to eight inches 

 and have been found up to two pounds in weight. Concentrated in seams, some of 

 the smaller ones consisting of pure corundum and the larger ones carrying 10 

 to 70 per cent corundum. U. S. G. S. says it is reported this deposit is a 

 good abrasive, and a fire test proves it can be used in the manufacture of a 

 vitrified wheel. Another deposit reported five miles west of this one, and a third 

 deposit 14 miles southwest of Bozeman. 



As a sapphire is found in gravel deposits on Rock Creek. Granite comity. 

 This deposit is being worked and practically the entire output goes into indus- 

 trial u.ses. 



CRYSTALLINE LIMESTONES AND MARBLES 



High grade deposits of marble are reported from a number of places in 

 Montana. There has been practically no commercial production, however. Near 

 Manhattan. Gallatin county, is a deposit of travertine onyx. Rowe reports the 

 stone is of good grade and the product similar to the Mexican variety and 

 that it takes a splendid polish. In Nelson Gulch, southwest of Helena, Lewis 



