448 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



The angles observed are given in the following table : 

 Angles on datolite from Mcriden. 



a /\m . 

 m /\m. 

 c/\k... 

 cAX .. 

 cA« -- 

 c/\n .. 

 c/\m . 

 cAt.. 

 cAg--- 



cAm^- 

 m^ A w 



GEDEITB VARIETY OF ANTHOPHYLLITE FROM CHESTERFIELD, 

 MASSACHUSETTS. 



Under " Cummingtonite," in his work on the minerals of Old 

 Hampshire County, Massachusetts, Prof. B. K. Emerson' gives the 

 following : 



The bair-brown hornblende, so long called anthophyllite, occurs in a highly 

 pyritous rock associated with large garnets, and can be best obtained in the 

 bluffs west of Bunnels Pond, in Chesterfield, and from large bowlders down 

 the hill nearly a mile southeast of Chesterfield church. 



The writer in April, 1919, visited what was presumed to be the 

 above locality, west of the pond in Chesterfield, marked Burnell's 

 Pond on the Holyoke topographic sheet, but now locally known as 

 Damon's Pond. In the eastern edge of a field of a deserted farm 

 topping the first rise west of the pond a bed was found which seemed 

 to answer Emerson's description. The bed, which is some 20 or 30 

 feet thick, outcrops boldly in the pasture, but nearly all of the loose 

 portions of the rock have been hauled away in clearing the land. At 

 the base of its outcrop this bed is made up of a coarse foliated mus- 

 covite rock containing numerous garnets which reach an extreme 

 diameter of 3 or more inches. In color they are reddish black, of a 

 dodecahedral form, with well-developed faces. The granular matrix 

 is readily worked away from the crystals and fine specimens can be 

 developed. Higher in the outcrop the garnet gives out, and the 

 upper part of the bed is made up of a coarse aggregate of a fibrous 

 brown material, in blades which may reach several inches in length, 

 associated with some muscovite and a little quartz and feldspar, to- 

 gether with considerable amounts of a mineral pleochroic in pale 



1 Bull. D. S. Geol. Surv., No. 126, 1895. 



