On Columhiie. 149 



Art. XIV. — On the Identity of the Torrelite of Thomson with 

 Columhiie; by James D. Dana, A. M., Assist, in the department 

 of Chem. Min. and Geol. of Yale College. 



Read before the Yale Nat. Hist. Soc. Feb. 21, 1837. 



In a late number of the Records of General Science, (Dec. 1836, 

 IV. p. 407,) Dr. Thomas Thomson has proposed a separation of the 

 Columbite of Middletown, in this state, (Connecticut,) from the spe- 

 cies heretofore designated by that name, and has denominated the 

 supposed new species Torrelite, in honor of our distinguished coun- 

 tryman, Dr. Torrey. He has been led to this result, by the dissimi- 

 larity which he appears to have obtained, between the specific gravity, 

 hardness, and composition of a specimen from the above locality, and 

 the same qualities of the Haddam and Bohemian specimens. From 

 an imperfect, and evidently very irregular crystal, he has also dedu- 

 ced a primary form, distinct from that of Columbite. The author of 

 these remarks, having had the pleasure of examining several of the 

 splendid crystals, remarkable for their regularity and brilliancy, af- 

 forded by the Middletown locality, would here state what appear to 

 be the obvious deductions from these crystals, respecting the propri- 

 ety of the above distinction. It should be premised, however, that 

 although the conclusion deduced may differ from Dr. Thomson's, 

 yet considering the apparent rhomboidal form of the only crystal in 

 his possession, and also the other discrepancies which he observed, 

 we must regard his conclusions as a fair deduction from the facts ob- 

 served. 



The identity of the Haddam and European specimens was clearly 

 exhibited by Dr. J. Torrey, by means of figures and descriptions, 

 in the Annals of the New York Lyceum, Vol. I. page 89. The 

 first of the following figures is copied from this article. To facilitate 

 comparison, a representation by Mr. Brooke, of a crystal in his pos- 

 session, (Fig. 2,) supposed from Bodenmais. in Bavaria, is added. 

 The general forms of these figures are modified rectangular prisms. 



Mr. Brooke obtained the following angles : 



P : o' = 1360 30' M ; 6=156° 30' 



P : e =120° M : e = 114° 30' 



With the reflective goniometer, Dr. Torrey found 



M : e and M : e = 157° M : e=. 129° 50' M : e'=102° 50' 

 The angles M t c approximate sufficiently to prove an identity. 



