540 R. P. D. Graham — Optical Properties of Hastingsite. 



spangolite. It will be recalled that the type specimen of 

 spangolite came from an unknown locality in southern Arizona. 

 With it were minute blue prismatic crystals, not determined 

 by Penh* eld, but suggesting connellite. While spangolite has 

 not yet been found at Bisbee, it now seems highly probable 

 that the original specimen came from there, and that it may be 

 rediscovered if carefully sought for. 



Mineralogical Laboratory, 



Harvard University, July, 1909. 



Art. LII. — On the Optical Properties of Hastingsite from 

 Dungannon, Bastings County, Ontario; by R. P. D. 

 Graham. 



In a paper which appeared in this Journal for July, 1894, 

 the discovery of a large area of nepheline syenite in the town- 

 ship of Dungannon, in the Province of Ontario, was announced 

 and the geological relations and mineralogical characters of 

 the mass were briefly described. Further exploration showed 

 that the nepheline syenites in this part of Ontario had a very 

 wide distribution and the results of a detailed study of them 

 has just appeared.* In the township of Dungannon, about 

 two miles east of the village of Bancroft, the nepheline syenite 

 contains a remarkable hornblende associated with a titaniferous 

 anclradite ; these minerals were analyzed by Dr. Harrington 

 and their chemical composition was discussed in a paper 

 which appeared in this Journal in March, 1896. f No thorough 

 examination of the optical properties of the remarkable horn- 

 blende, however, has hitherto been made, and the writer, at the 

 request of Dr. Adams, has studied the mineral with a view to 

 the determination of its optical characters. 



The material employed was that obtained by Dr. Adams at 

 the original locality above mentioned. 



The hornblende is distributed throughout the rock in fairly 

 large amount as small black individuals or aggregates with a 

 high luster, especially on the cleavages ; but no fragments 

 having crystal faces were found on the specimen examined. 

 Except in very thin flakes, it is practically opaque. 



* The Nepheline and Associated Alkali Syenites of Eastern Ontario, by 

 Frank D. Adams and Alfred E. Barlow : Trans. Eoyal Society of Canada, 

 1908-09. 



f On a new Alkali Hornblende and a titaniferous Andradite from the 

 Nepheline Syenite of Dungannon, Hastings Co., Ontario, by Frank D. Adams 

 and B. J. Harrington. 



