Genth.] ou - 1 [Sep. 19, 



Green Mountains. The gneiss contains no corundum ; the talcose rock, 

 however, has grains of emery, corundum and magnetite disseminated 

 through the whole mass ; a vein of oligoclase (so-called indiauite) many 

 inches in thickness with small particles of corundum diffused through it, 

 runs for many rods through the chloritic rock. 



The corundum is generally in small brownish crystals, or very fine 

 grains ; the variety sapphire is sometimes met with in bi-pyramidal crys- 

 tals ; pinkish margarite, disapore and corundophilite frequently invest 

 the corundum or emery, which is also associated with tourmaline, cyanite 

 chloritoid, ilmenite, rutile, etc. With the oligoclase occurs a dark-green 

 variety of biotite. 



The views of Jackson, endorsed by Shepard, that the Chester (Mass. ) 

 emery was a distinct mineral species and that it had the composition of 

 hercynite, FeO, Al 2 3 , has already been refuted by J. L. Smith. 



I will here mention a few other New England localities of corundum, 

 although they may not belong to the chromiferous serpentine region. 



J. H. Adams* observed it in small quantity and rarely in situ at Pel- 

 ham, Mass., in flattened masses of a brownish-black mica (Biotite, 

 Shepardf) containing nodules of corundophilite (Vermiculite, Shepardf) 

 inclosing white and sapphire-blue corundum. 



At Litchfield, Conn., it is found in balls of cyanite, constantly associ- 

 ated with talc and diaspore (Shepardf) ; and at Norwich, Conn., in small 

 crystals of sapphire-blue color, completely surrounded by fibrolite 

 (Shepardf). 



In Pennsylvania corundum is found in many localities between the 

 serpentine and the granitic and gneissoid rocks, commencing near the 

 Blue Hill, in Upper Providence Township, and extending for about five 

 miles to near Rockdale, Middletowu Township, Delaware County ; and 

 again appearing near Unionville, in Newlin Township, Chester County. 



At Mineral Hill and the Black Horse, near Media, Delaware County, 

 occurs a feldspathic rock, consisting of a triclinic feldspar of a yellowish- 

 white or white color and granular structure, and showing striation very 

 distinctly on some of the cleavage planes. A great part of it is already 

 changed into kaolinite. It appears to be free .from quartz, but dissemi- 

 nated through the mass are crystals of corundum more or less altered 

 into fibrolite and a micaceous mineral, probably damourite ; many loose 

 crystals of corundum are found in the soil. 



At Unionville, Chester County, crystals of corundum have been fre- 

 quently met with in the soil, and even large boulders are not of unusual 

 occurrence ; a little over one year ago, the bed from which these evidently 

 came was discovered. At the time of my visit I could see a mass of 

 almost solid corundum about thirty feet in length, from five to ten feet in 

 thickness, with a depth of about fifteen feet. The corundum is of a 

 granular structure, a brownish-grey color, and like the crystals which 



*J. H. Adams-Sill. Journ. [2] XLIX , 272. 

 t C. U. Shepard— Sill. Journ. [31 IV, 179-1S0. 



