PALACHE AND PRAPRIE. — BABINGTONITE. 391 



in which the larger portion of the babingtonite slowly settled, leaving 

 floating all fragments with adhering prehnite. About 3 grammes 

 was thus obtained, which under the microscope showed no appreciable 

 impurity. 



The analysis, by Fraprie, was made according to the method of Hille- 

 brand for silicate analysis, except that the manganese was precipitated 

 with bromine water. 



Analysis. Recalculated to 100% Mo i ecular Rat io. 



' omitting II 2 0. 



SiO, 52.25 52.66 0.8777) 



Ti0. 2 0.18 0.18 0.0023 j 



A1 2 3 5.27 5.31 0.0521 



Fe 2 3 7.49 7.55 0.04 



FeO 11.05 11.14 0.1547] 



21 1 



I 1 0.0993 1.00 



47 

 MnO 1.94 1.96 0.0276 I 



CaO 20.36 20.52 0.3664 ^ 0.5630 5.67 



MgO 0.46 0.46 0.0115 



(K,Na) 2 0.22 0.22 0.0028 



Loss (H. 2 0) 0.29 



Total 99.51 100.00 



The analysis shows a babingtonite somewhat lower in manganese and 

 much higher in aluminum than the average, but otherwise of normal 

 character. It may be expressed by the formula, 



(Ca,Fe,Mn) Si0 3 ■ (Fe,Al) 2 (Si0 3 ) 3 



with the two molecules present in the proportion of about 5| : 1. 



2. Babingtonite from Athol, Mass. 



Babingtonite was first reported from Athol by Shepard * in 1849, and 

 the locality was cited for the mineral in his Mineralogy, 1857, p. 183. 



J. D. Dana was the first to examine the crystals critically, and his 

 measurements, made on very small crystals, were not conclusive, as they 

 agreed but poorly with the angles of babingtonite from Arendal. His 

 figure and measurements are to be found in his Mineralogy, 1854, 

 p. 368, and the question of the identity of this mineral has remained unset- 

 tled. In Dana's System, 1892, reference is simply made to the descrip- 

 tion cited above, the matter being still left in doubt. 



* A. J. Sci., VIII. (1849), p. 275. 



