CONTRIBUTIONS FROM THE HARVARD MINERALOGICAL 



MUSEUM. —XII. 



1. BABINGTONITE FROM SOMERVILLE, MASS. 



2. BABINGTONITE FROM ATHOL, MASS. 



By C. Palache and F. R. Fraprie. 



Presented by J. E. Wolff, October 8, 1002. Received October 8, 1902. 

 BABINGTONITE FROM SOMERVILLE, MaSS. 



Occurrence and Paragenesis. 



The occurrence of babingtonite at Somerville has long been recorded, 

 but no adequate description of it seems to have been published. We first 

 find mention of it in a description by Teschemacher * of the minerals of 

 the Charlestown sienite quarry, where it is called "hornblende in the 

 form of oblique rhombic prism with modifications c, k, 1 ; crystals are 

 small and black on white prehnite." 



In Alger's Phillip's Mineralogy, 1844, p. 79, it is stated on the author- 

 ity of Professor Nuttall that babingtonite occurs at Charlestown and 

 that this is the only American locality. No description of the mineral 

 by Nuttall has been found, and Alger probably had the information 

 ))rivately from Nuttall. This statement was copied in Brooke and 

 Miller's Mineralogy (1852), but appears never to have found its way 

 into the American text-books, tlie only further mention of it being iti 

 Dana's System (1892), where, although not referred to in the text, the 

 mineral is listed in the Catalogue of Localities, p. 1059, as occurring at 

 Somerville. 



The babingtonite occurs in veins and pockets composed chiefly of 

 prehnite, which traverse a large dyke of diabase.f This dyke is well 

 exposed in an old quarry, recently abandoned, on Granite Street, Somer- 



♦ Proc. Boston Soc. N. H., June, 1839, in Am. J. Sci., XXXVIII., 1840, p. 104. 



t For a description of tliis rock, which is called sienite in all of the above refer- 

 ences, ."^oe Wadsworlli, Troc. Hos. Soc. N. II., XIX. (1870), p 223, and Jaggar, Am. 

 Geol., XXI. (1808), pp. 203-213. 



