470 T. L. WATSON WEATHERING OF ALLANITE 



Neiu YorJc. — Of the large number of interesting minerals found in the 

 pegmatites of Port Henry and vicinity, Essex County, New York, allanite 

 has been reported in unusual amount and in crystals of exceptional size 

 and perfection. ^^ In a coarse pegmatite which accompanies the magnetite 

 at the Smith mine, Mineville, more particularly in the Cook shaft, allanite 

 occurs at times in great abundance, and, according to Kemp,"^ is richly 

 disseminated in irregular crystals up to the size of one's hand. Newland 

 states^^ that at one time there was a large accumulation of waste rock on 

 the ground from which allanite could be obtained in specimens up to 

 several pounds in weight, and mentions one large piece of probably 15 or 

 20 pounds weight which he obtained several years ago. 



Some fine specimens of allanite have come from the Sanford ore bed 

 (now called "Old Bed'' mine), 2 miles south of the Smith mine, where 

 the occurrence has been described by W. P. Blake^^ and E. S. Dana.^^ 

 Crystals 8 or 10 inches long, 6 or 8 inches broad, and 1 to 2 inches thick 

 are mentioned. The mineral is no longer available. 



Kemp gives a large list of interesting minerals in the pegmatites of the 

 Elizabethtown and Port Henry quadrangles. These are allanite, apatite, 

 amphibole, albite, arsenopyrite, biotite, fluorite, garnet, lanthanite, mag- 

 netite, molybdenite, pyrite, pyroxenite, quartz, titanite, wernerite, and 

 zircon.^* 



At Mounts Adam and Eve, Warwick, Orange County, Kemp^^ reports 

 allanite as "frequent in the granite from the quarries on Adam and Eve, 

 and also in especially large amount in rather coarse pegmatitic masses of 

 feldspar and quartz, that occur in the stone, etcetera." The allanite is 

 found in crystals and masses and is extremely brittle. In sections the 

 mineral is yellowish brown to seal brown, and, as usual, is strongly pleo- 

 chroic. It is accompanied by purple fluorspar, which appears along the 

 edges of the crystals. It is also said to be bounded at times "by a lighter 

 colored brown rim of what is probably slightly decomposed allanite. The 

 optical properties of the Edenville allanite have been measured by Michel- 

 Levy and Lacroix, who determined the mean index of refraction to be 



29 .T. F. Kemp and R. Rucdemann : Museum Bulletin 138, N. Y. State Museum 1910 

 pp. 125, 126, 153-154, 



J. F. Kemp : Trans. Am. Inst. Mln. Engrs., vol. 27, 1897, p. 195. 



J. F. Kemp : Am. Jour. Sci., vol. 40, 1890, p. 62. 



H. Ries : Trans. N. Y. Acad. Sci., vol. 16, 1897, pp. 327-329. 



30 J. F. Kemp : Op. cit, 1910, p. 154. 



^ D. H. Newland : Personal communication, September 25, 1916. 



32 W. P. Blake: Am. Jour. Sci., vol. xxv, 1858, p. 259; ibid., vol. 26, 1858, p. 346. 



33 E. S: Dana : Am. Jour. Sci., vol. xxviii, 1884, p. 479 ; Groth's Zeitschr., Bd. 9, p. 283 

 3* J. F. Kemp : Op. cit, 1910, p. 153. 



35 J. F. Kemp : N. Y. Acad. Sci., vol. vii, 1892-1894, pp. 638-650. 



