EMERY MINE OF CHESTER, MASS. 53 



it to be. both chemically and physically, a chlorite, identical 



no doubt with the chlorite I found associated with the emery 



of Asia Minor. Both the Asia Minor and Chester varieties 



occur in compact mass, composed of an agglomeration of small 



crystalline plates — identical with the chlorites of Mont des 



Sept-Lacs and of St. Christoph?, and the ripidolites of Eauris 



and St. Gothard. In the following analysis I do not pretend 



to furnish that of the pure mineral, as from the thinness of the 



layers in the specimens at my disposal it can not be separated 



in that state of purity I am in the habit of seeking for in all 



minerals that I examine : 



Silica 25.06 



Alumina - 30.70 



Protoxide of iron 16.50 



Magnesia 16.41 



Water 10.62 



99.29 



The optical characters were not examined, there being no 

 means at hand. 



I may remark that the alumina and magnesia were sepa- 

 rated by resolution and reprecipitation three times. 



Tourmaline. — This mineral is also found with the emery of 

 Chester in the same manner as with the emery of Naxos. 



Titaniferous iron (ilmenite). — This is found principally in 

 flattened crystals in the margarite. 



Oxide of titanium (brookite or rutile.) — With the diaspore 

 we found some beautiful flattened hair-brown crystals. The 

 specimen in my possession does not furnish the face of the 

 crystals so as to enable me to make out what form of titanium 

 oxide it is. Prof. Shepard thinks he has sufficient evidence to 

 pronounce it to be brookite. 



Magnetic oxide of iron — This ore of iron is found in great 

 abundance associated with the emery, and is worked for the 

 manufacture of iron ; it contains a little oxide of titanium. 



The above, as well as some other associated minerals of less 

 importance, justify the concluding remarks of my paper on 

 emery fifteen years ago, viz. : " I do not risk much in saying 

 that the hydrate of alumina or diaspore, as well as the silicates, 

 as emerylite, chlorite, and tourmaline, and the minerals of iron, 

 as magnetic, titaniferous iron, etc., will be found almost every 

 where with the emery and corundum." 



5 



