210 Kraus and Cook — Iodyrite from Tonopah. 



Art. XIII. — Iodyrite from Tonopah, Nevada, and Broken 

 mil, New South Wales / by E. II. Kraus and C. W. Cook. 



In November last the Mineralogical Laboratory of the Uni- 

 versity of Michigan received a consignment of minerals from 

 the Foote Mineral Company of Philadelphia, Pa., which con- 

 tained ten selected crystals of iodyrite from Tonopah, Nevada, 

 a new locality for this mineral. Our attention was called to 

 this fact by Mr. W. M. Foote, manager of the company. On 

 examination, several of these crystals showed that they pos- 

 sess a pronounced hemimorphic development, and also several 

 forms which had not as yet been observed on iodyrite. We 

 immediately informed Mr. Foote of these facts and he most 

 cordially placed a very liberal quantity of selected material at 

 our command. He subsequently sent us a specimen from 

 Broken Hill, New South Wales, which contained crystals of a 

 most interesting character. 



Through the courtesy of Director H. C. Bumpus and 

 Curator L. P. Gratacap of the American Museum of Natural 

 History of New York City, we w T ere able to examine speci- 

 mens 2609 and 2610 of their mineral collection. The first of 

 these is from Broken Hill, the second from Chile. 



The various contributions on iodyrite are rather fragment- 

 ary and also widely separated in time. It was, therefore, 

 deemed advisable to preface the results of our study with a 

 brief survey of the work already done on this mineral. 



Historical. 



In 1825 Vauquelin* pointed out that certain silver ores from 

 Mexico contained the element iodine, probably in the form of 

 the iodide. This was the first record of the occurrence of the 

 element iodine in the mineral kingdom, it having been previ- 

 ously observed only in plants and animal remains. Cantuf 

 had, however, showed the presence of iodine in traces in cer- 

 tain mineral waters from Asti, Italy. That silver iodide occurs 

 in nature was first definitely pointed out by Domeyko,J who 

 in 1844 analyzed material from Chanarcillo, Chile. As to the 

 crystallographic development of this material the only state- 

 ment made by Domeyko is that rhombohedral-like forms were 

 occasionally observed and also that the structure was more or 

 less lamellar. Domeyko did not make a complete analysis but 

 showed conclusively that the amount of silver in the natural 



* Annales de Chimie et de Physique, xxix, 99, 1825. 

 f Annales des Mines (4), vi, 158, 1844. 

 % Cited by Vauqiielin, loc. cit. 



