THE MINING AND QUARRY INDUSTRY I909 33 



the output, two producing" slip clay; one, lire clay; one, paper 

 clay; and three, potters clay. 



EMERY 



The emery mines in Westchester county increased their out- 

 put last year by about 200 tons. The product reported was 

 892 short tons valued at $10,780 as compared with 690 short 

 tons valued at S8860 in 1908. The production was still con- 

 siderably below the averag'e as the annual shipments have 

 usually exceeded 1000 tons. The poor showing may be at- 

 tributed to a decrease in the demand for abrasives which was 

 noted as well in other branches of the productive industry. 



The statistics of output are based upon the crude material as 

 shipped from the mines where it undergoes only a rough sort- 

 ing or cobbing. The emery is mainly shipped to Pennsylvania 

 for grinding and manufacture. The producers in 1909 w r ere as 

 follows : Blue Corundum Mining Co., Easton, Pa., Keystone 

 Emery Mills, Frankford, Pa., and the Tanite Co., Stroudsburg, 

 Pa. The Hampden Corundum AYheel Co. of Springfield, Mass., 

 and J. R. Lancaster of Peekskill who in the past have been 

 actively engaged in the industry made no output last year. 



The New York emery is a mixture of corundum, spinel and 

 magnetite in varying proportions. It occurs as a hard, dense 

 rock, of dark gray to nearly black color, sometimes showing 

 the corundum in well developed prismatic crystals of lighter 

 shade. The corundum, which of course is the more valuable 

 constituent, may constitute as much as 50 per cent of the entire 

 mass, or it may be subordinate to the other ingredients. The 

 emery occurs in the form of lenses and bands within basic 

 igneous rocks of the gabbro family. It is the result of segrega- 

 tion of the heavier rock minerals, and the deposits are analo- 

 gous to the bodies of titaniferous magnetites which occur in 

 gabbroic rocks. Some of the deposits, indeed, contain a fairly 

 high percentage of magnetite and were once mined for iron ore. 

 but the material proved too refractory for use in the blast 

 furnace. 



1 T.LDSPAR 



There was no notable change in the feldspar industry during 

 [909. The demand for the better quality ^i feldspar which is 

 used in pottery manufacture continued dull and prices showed 



