£50 Goldschmidt and Nicol — New Forms of Sperrylite. 



Art. XLY. — New Forms of Sperrylite; by Victor Gold- 

 schmidt and William Nicol. 



The sperrylite examined by ns during the summer of 1902 

 was obtained at the Vermillion Mine, Algoma District, Province 

 of Ontario. This is the original locality from which was ob- 

 tained the material examined by Wells and Peniield* and that 

 described by Walker. f By "panning" the loose material at 

 the month of the old shaft a heavy residue was obtained. 

 When this residue was examined by a needle and pocket lens 

 the brilliant silver-white crystals of the mineral were readily 

 separated from the magnetite, etc., occurring with them. The 

 crystals are exceedingly small, but on account of their brilliant 

 metallic lustre the measurement of the minute faces was easily 

 possible. The crystals were measured on the two-circle reflect- 

 ing goniometer, making use of the reduced signal. 



Nine crystals were measured, which showed the following 

 forms : 



Crystal System Regular. Pentagonal Hemihedrism. 



** ** * * * * *#■* 



Letter : cag - ehb - <3kmqBpui/>x 



Symb.Gdt.: + *0 -fO +#> +|0 --§0 -10 \ 1 \ f 1 \\ U ~U 

 Symb. Miller: 001 103 205 102 305 203 101 114 113 112 335 111 212 214 213 



Of these forms, those designated with an asterisk are new for 

 sperrylite. In addition to these, two other forms, 

 ?z=+«(315); ?D = +ii(326), 

 were observed, but not with absolute certainty. 



Charles W. Dickson, £ doing post-graduate work at the School 

 of Mines, Columbia University, New York, has succeeded in 

 separating sperrylite crystals from the unaltered chalcopyrite 

 from the Victoria Mine, in the Sudbury District. He reports 

 by letter, " I found, on examination of two of the best crystals, 

 the trapezohedrons 211 and 411, besides the originally described 

 forms." 



The form e occurs on all the crystals measured, having only 

 half the number of faces developed, in accordance with penta- 

 gonal hemihedrism. This form has been regarded as positive, 

 and the positive or negative character of the other forms has 

 been determined in accordance with this. This criterion may 

 be accepted as decisive. On account of the minute size of the 

 crystals it was not possible to attempt to decide this point by 

 etch-figures. 



* This Journal (3), xxxvii, 67 et seq., 1889. Zeitschr. f. Kryst., xv, 285 u. 

 290, 1889. 



f This Journal (4), i, 110 et seq., 1896. Zeitschr. f. Kryst., xxv, 561, 1895. 

 % This Journal (4), xv, 137, 1903. 



