Dickson — Platinum in the Nickel-Copper Ores. 139 



Faces. 

 100 ^ 100 



t< 



100/vlll 



111^111 

 210^100 



Observed Angles. 



Calculated Angles. 



90° 3' 



90° 



90° 1' 



a 



54° 41' 



54° 44' 8" 



54° 46' 



it 



70° 28' 



70° 31' 44" 



70° 29' 



a 



26° 40' 



26° 34' 



" 26° 38' " 



211 A 100 35° 14' 35° 15' 45" 



35° 11' " 



A somewhat smaller crystal yielded a variety of forms, 

 including two trapezohedrons (211 and 411), with the follow- 

 ing measurements : 



Faces. Observed Angles. Calculated Angles. 



211^111 19° 28' 19° 28' 30" 



" 19° 24' " 



411^111 35° 17' 35° 15' 45" 



" 35° 18' " 



The dodecahedron (110) was also observed on a number of 

 crystals. It was noticed that the octahedral faces gave the 

 best reflections, while those from the trapezohedrons were 

 fainter, and those from the cube were often multiple. 



Of the faces found, the trapezohedrons (211 and 411) had 

 not been recognized till the work of Professors Nicol (School 

 of Mining, Kingston, Ont.) and Goldschmidt, during the past 

 summer.* In addition to the forms already described (111, 

 100, 102 and 110), these workers discovered a large number of 

 new and interesting faces, including the two found on this 

 material. It is thus evident that the sperrylite from the new 

 source and locality ^Victoria mine) is identical, chemically and 

 mineralogically, with that as originally described by Professors 

 Penfield and Wells from the Vermilion mine. 



While these experiments will not prove that all the platinum 

 is present as sperrylite, they at least remove the doubt as to its 

 condition, in part at least, in the unaltered ore. Even the plati- 

 num which has been found in connection with the nickel mineral 

 polydymite will no doubt prove to be present as the arsenide, 

 if enough material can be made available for careful work.f 



These experiments were carried on, partly in the laboratory 

 of the School of Mining, Kingston, Ont., which was kindly 

 placed at the writer's disposal, and partly in the laboratories of 

 the Geological and Mineralogical Departments, Columbia Uni- 

 versity, and thanks are due to Dr. W. L. Goodwin, of Kingston, 

 and Professor Kemp, of Columbia, for facilitating the work. 

 The writer is also indebted to Dr. A. F. Rogers, of the Depart- 

 ment of Mineralogy, Columbia, for his kindness in assisting 

 with the goniometrical determinations. 

 Columbia University, New York, Dec. 12, 1902. 



* This Journal (4) xv. f This Journal (3), xxxvii, 67, 1889. 



