REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1903 163 



lu 1899 some garnet was imported from Africa, but on practical 

 test it was found to be inferior to the New York State material, 

 and its importation was discontinued. 



Uses of garivet 



The ready cleavage of garnet makes it a most valuable abrasive 

 in the leather and wood industries. Quartz and emery rapidly 

 become dull, but the garnet, owing to its brittleness along 

 cleavage planes, continually presents sharp cutting edges. The 

 various grades of garnet paper are known commercially as sand- 

 paper, garnet paper or shoe paper. It is of some use in the polish- 

 ing and grinding of brass, but foT other metals emery is con- 

 sidered better. A manufacturer of paper mill machinery has 

 used garnet in place of emery for grinding joints of ironwork 

 where the mineral is confined between two surfaces. In com- 

 parison with emery, only one half of the weight was required, 

 and a perfect joint was secured in half the time.^ 



Garnet has been mixed with emery and corundum in w^heels, 

 but the combination was not successful. 



Emery 



Emery occurs within the United States at three localities 

 along the Atlantic seaboard and at one or two places in the 

 middle west. The eastern deposits are the most fully developed, 

 and of these that at Chester Mass. is the most prominent. 

 Emery is found in New York about 4 miles southeast of Peek- 

 skill and 2 to 3 miles east of the Hudson river. It occurs in a 

 series of igneous rocks which have been intruded into the meta- 

 morphosed sediments of this region. These intrusions cover an 

 area of over 15 square miles, lying mostly within the town of 

 Cortlandt, whenc-e they derive the name of the " Cortlandt 

 series " given to them by J. D. Dana in 1880 .^ This series con- 

 sists mainly of rocks of the gabbro family. Norites, diorites and 

 peridotites are by far the most abundant. The principal asso- 

 ciate of the emery deposits is a norite. 



^Min. Ind. 9:299. 



^\m. .Jour. Sci. Ser. 3. 1880. 20:199. 



