ABRASIVE MATERIALS 435 



stone. In Rowan county, N. C, a granite is fiuarrird and 

 manufactured into millstones, which are sold, for the most 

 part, in North Carolina and Georgia. 



Whereas formerly a large number of huhrstones were 

 used in the United States, principally in grinding wheat, now 

 very few are used for that purpose on account of the intro- 

 duction of the rolling mill process. 



The greater part of the garnet that is mined for al)rasive 

 purposes, except the production from North Carolina, is used 

 in the manufacture of garnet paper, which is extensively 

 employed for abrasive purposes in the manufacture of l)oots 

 and shoes. Nearly all the production from North Carolina 

 is manufactured into wheels, which are sold as emery wheels. 

 The abrasive value of garnet was known to the North Ameri- 

 can Indians, who engraved shells with tools consisting of gar- 

 net points attached to wooden handles. 



In Connecticut, near Roxbury, Litchfield county, garnet 

 is obtained from a mica-schist, in which it occurs in crystals 

 from less than a quarter of an inch to nearly two inches in 

 diameter. As the rock is crushed the crystals readily separate 

 from the schist, making a clean granite concentrate, that is 

 ready for crushing and sizing. 



The principal New York garnet locaUties are near North 

 river, in Warren county, and in Essex county. The mineral 

 occurs in segregated masses, in both, gneiss and Hmestone rocks 

 varying in size from that of a pigeon's egg to that of a diameter 

 of 200 feet. Commercially, this garnet is designated (1) as 

 massive garnet, when it is in the larger masses, which are im- 

 pure ; (2) as shell garnet, which is nearly pure garnet ; and (3) 

 pocket garnet, when it occurs in small masses or crystals in the 

 gneiss. Of these, the shell garnet is considered the most val- 

 uable. 



The North Carolina garnet deposits that have been de- 

 veloped are all in Jackson county. The principal mine is on 

 Sugar Loaf mountain, about one and one half miles from the 

 raikoad. The occurrences are all similar, being bands of gar- 

 netiferous gneiss in ordinary gniess. These bands are 50 or 

 more feet in width, and average from 15 to 30 per cent of gar- 

 net. 



