82 S. L. Penfield — Connellite from Cornwall. 



brownish, but regains its green color on cooling without having 

 suffered loss in weight. In an unpowdered condition it decrepi- 

 tates rather violently on further heating, and, as originally- 

 stated, fuses readily to a red-brown liquid. In regard to the 

 evidence as to the condition of oxidation of the iron and tellurium 

 in emmonsite afforded by boiling the mineral with hydrochloric 

 acid, I would add that my former experiment was carefully 

 made and the products of distillation were collected in a solution 

 of potassium iodide. No evolution whatever of iodine was 

 observed. While this would not prove the entire absence of a 

 ferrous tellurate, it does prove conclusively, as indicated in my 

 original paper, that the mineral is chiefly a ferric tellurite. This 

 being true, it would be reasonable, even without other evidence, 

 to conclude that the mineral is simply a ferric tellurite and not a 

 combination of ferric tellurite with ferrous tellurate. 



"Washington, May 31, 1890. 



Aet. XI. — On Connellite from Cornwall, England; 

 by S. L. Penfield. 



The rare Cornish mineral, Connellite, was first described as 

 a new species by Prof. Connell, who presented, in 1847, at a 

 meeting of the British Association for the Advancement of 

 Science,* a short communication in which he stated that from 

 qualitative tests he had proved it to be a sulphato-chloride of 

 copper containing water. The name Connellite was first given 

 by Prof. J. D. Dana, in the third edition of his Mineralogy, 

 1850. In the fifth edition of his Mineralogy he also gives a 

 reference to the mineral as early as 1802, by Rasleigh,f who 

 calls it a " copper ore of an azure blue color, composed of 

 needle crystals," from "Wheal Providence. In 1863 Maske- 

 lyne;}: published a description of the crystals, in which he deter- 

 mined the form as hexagonal, habit slender prismatic, with 

 holohedral pyramidal terminations. Owing to their small size 

 (crystals being not over ^^ inch in diameter), he was unable 

 to measure the angle of the terminal faces on the ordinary re- 

 flecting goniometer, but by means of a microscope attachment 

 to his goniometer he was able to measure them with a fair de- 

 gree of accuracy. He identified two prisms, a pyramid of the 

 first order, and a di-hexagonal pyramid. He gives two figures, 

 one of which is copied in the fifth edition of Dana's Mineral- 

 ogy, the other representing a simpler combination of prism of 

 the second with pyramid of the first order. 



* Report of the British Association for 1847. f Brit. Min., ii, 13, pi. 12, f. 1, 6. 

 X Phil. Mag., IV, xxv, 39. 



