Kraus and Cook — Iodyrite from Tonojpah. 211 



compound agreed very closely with that of the artificial prod- 

 uct. Crystals from this same locality, which were in the 

 mineral collections of the Ecole de Mines, Paris, were meas- 

 ured by Des Cloizeaux* in 1854. Des Cloizeaux assigned the 

 mineral to the hexagonal system and calculated the axial ratio 

 to be a: c = l: 0*81438. The nine forms observed by him are 

 given in the tabulation on page 21 Y. Although it is not clear 

 that Des Cloizeaux observed hemimorphism, it is, neverthe- 

 less, of interest to note that he pointed out the very close simi- 

 larity of the angles of the natural iodide of silver and the 

 hemimorphic mineral greenockite. 



In 1851 Danaf suggested the name iodyrite for this mineral, 

 although Haidinger^: had previously (1845) called it iodite. 

 The name iodyrite has become international in spite of the 

 fact that Leymerie§ introduced iodargyrite in 1859. 



The next contribution to our knowledge of this compound 

 was made in 18Y9 by Zepharovich,|| who carried out a rather 

 extensive examination of artificial crystals, w T hich had been 

 prepared by Belohoubek. In all Zepharovich observed twelve 

 forms, seven of which had, however, been previously noted 

 by Des Cloizeaux on natural crystals ; see the tabulation on 

 page 21 Y. It is of some interest to indicate in this connection 

 that although the hexagonal prism of the first order is, accord- 

 ing to Des Cloizeaux, a common form on iodyrite, it was, 

 nevertheless, not observed by Zepharovich on artificial crystals. 

 Zepharovich established a new axial ratio which differed con- 

 siderably from the one obtained by Des Cloizeaux. Accord- 

 ing to Zepharovich the ratio is as follows: a:c=l: 0*8196. 

 These values have been generally adopted. T The crystals 

 examined by Zepharovich possessed a pronounced hemimorphic 

 development. 



In 1881 Seligmann** examined crystals of iodyrite from 

 Dernbach, Nassau, and observed seven forms ; see page 21Y. 

 The development of these crystals was such as to point to 

 hemimorphism in that £[2021 1, 6>jl011^, and ^j4041[ were 

 observed above the prism of the first order while a' j 2021} was 

 noted below. Seligmann also examined crystals from Chile 

 and on these noted four forms which had not been observed 

 on either natural or artificial crystals of silver iodide ; see page 



* Armales de Chimie et de Physique, xl, 85, 1854. 



f System of Mineralogy, 4th edition, 95, 1854. 



X Chester, A Dictionary of the Names of Minerals, 189G, 134. 



§ Chester, loc. cit. 



|| Zeitschr. Kryst., iv, 119, 1879. 



^[Dana, System of Mineralogy, 6th edition, 1892, 160; Groth, Tabella- 

 rische Uebersicht der Mineralien, 4th Auflage, 1898, 50 ; Naumann-Zirkel, 

 Elemente der Mineralogie, 14te Anflage, 1901, 505. 



** Zeitschr. Kryst. vi, 229, 1881. 



