32 NEW YORK STATE MUSEUM 



mica and 'chlorite is an element of weakness, inasmuch as they pro- 

 vide surfaces along which the garnet fractures more or less readily. 

 An imperfect cleavage or parting that results from regional com- 

 pression, however, is not detrimental and may be an advantage if 

 not too pronounced. The color of garnet can not be used as a 

 criterion of quality, but abrasive manufacturers usually express a 

 preference for the dark shades which show a good red color when 

 applied to paper or cloth. It is important, also, that the garnet 

 crystals be sufficiently large so that when crushed and separated 

 from the rock matrix the garnet will not be too fine but will afford 

 the desirable assortment of sizes. The normal result of milling 

 a small crystal is to produce an excess of the finer sizes. Much of 

 the garnetiferous rock that occurs in various parts of the Adiron- 

 dacks and elsewhere can not be utilized because of the small 

 crystal, if for no other reason. 



Besides the Adirondacks, North Carolina and New Hampshire 

 have supplied some abrasive garnet in recent years, and mines now 

 inactive are found in several other states within the Appalachian 

 metamorphic belt. 



The wood-working and leather manufacturing industries are the 

 principal consumers of garnet which is used in the form of garnet 

 paper and garnet cloth. " Ruby " paper is a common name for the 

 manufactured material. Its efficiency is said to be several times 

 greater than ordinary quartz sandpaper. 



The garnet mines in the Adirondacks were first developed for 

 commercial production about 1882. The earliest operations were 

 on Gore mountain, in connection with the remarkable deposit 

 known as the Rogers mine. This is by far the richest of the mines 

 and as already stated is worked by hand. The output for the first 

 few years probably did not amount to more than a few hundred 

 tons annually. By 1893, however, it had grown to 1475 tons, 

 according to figures published in The Mineral Industry. The next 

 important development came with the introduction of mechanical 

 methods for the separation of the garnet, due to the initiative of 

 the Messrs Hooper who constructed the first mill on a property 

 lying a little west of North River in the town of Minerva, Essex 

 county. The garnet here occurred in smaller crystals than in the 

 Rogers mine and could not be economically handled by the methods 

 adopted at that mine. The North River Garnet Co. later built a 

 mill which it now operates on Thirteenth lake, Warren county, the 

 first mill having been dismantled. The production of garnet from 

 1904 to date has been as follows : 



