164 PROCEEDINGS OF THE AMERICAN ACADEMY. 



yellow or amber colored crystals were separated by hand-picking under 

 a powerful lens. Aside from a slight stain in a few crystals the only 

 impurities visible under the microscope were minute adhering grains of 

 octahedrite and aegirite hardly amounting to more than a trace. 



The result of the chemical analysis made on these crystals is as 

 follows : 



Spec. G. 4.320 



The molecular ratios derived from the above analysis are : — CO2 : 

 F : II2O3 : CaO = 0.549 : 0.345 : 0.178 : 0.205. This may be written, 

 CO2 : F : R3O3 : CaO = 3 : 1.88 : 0.97 : 1.11 which equals very nearly 

 3:2: 1 : 1. This ratio leads to the formula (R"F)2 Ca(C03)3, 

 which is the same as that derived for the mineral by Penfield and 

 Warren ^^ from analyses of the mineral from the original locality, Muso 

 valley, U. S. of Colombia and a locality in Ravalli Co., Montana. The 

 chemical composition throughout of the Quincy mineral is very close 

 to that of the parisite from the other localities mentioned. The for- 

 mula also agrees with that derived for the barium -bearing mineral from 

 Greenland. Synchisite, although identical with parisite in its crys- 

 tallographic and essentially so in its optical constants and in the ele- 

 ments present, contains, according to the analysis of Flink, one more 

 molecule of calcium carbonate, the formula for the synchisite being 

 (R"F)2Ca2(C03)4. It is true that the two minerals differ perhaps 

 slightly in specific gravity and in the value for the extraordinary ray. 

 The relationship deserves further investigation. 



For a more complete discussion of the relationship of these minerals 

 and the crystallography of the parisite, see a paper by Palache and 

 Warren.^* 



Ilmenite. — Ilmenite occurs in moderate abundance in both the 

 Ballon and Fallon pegmatites. It appears to have been of rather late 



" Am. J. Sci. 8, 21 (1899). 



" Zeits. f. Kryst., 49 (1911), and Am. J. Sci., 31, 533 (1911). 



