A. F. Rogers — Pyrite Crystals from Bingham, Utah. 467 



Akt. XLI. — Pyrite Crystals from Bingham, Utah; by 

 Austin F. Rogers. 



The pyrite crystals described in this note were kindly pre- 

 sented to the writer by Dr. A. L. Inglesby of Bingham, Utah. 

 They were obtained by him from the Highland Boy mine in 

 Carr Fork, about a mile and a half above Bingham. The 

 crystals, which average about 5 mm in diameter, are well 

 developed, have brilliant faces, and are often highly modified. 

 The best groups of crystals in Dr. Inglesby 's collection are 

 magnificent specimens, rivaling those from Leadville and from 

 Central City, Colorado, in attractiveness. 



The observed forms are as follows : cube, a \ 100 J; pyrito- 

 hedrons. <?J210|, 6>5430(, 8j610f; trapezohedrons, n\211\, 

 wi|311 1, /*|411|; positive diploids,*) 321 f,^{12-9-l|,/)|10-7-l |; 

 negative diploids, T{ 8-10-5} and <9j371}. Of these the last 

 four are new for the mineral pyrite. 



The habit is determined either by the cube or by the pyrito- 

 hedron \ 210 \ , often in about equal development. ~No tendency 

 toward an octahedral habit was noticed: — a\100\ varies from 

 a mere line face to the .dominant form. It is often striated 

 parallel to its intersection-edge with |111 }; <?j210[ is on most 

 of the crystals the dominant form. It is sometimes striated 

 parallel to its intersection edge with jlllf and J321} and only 

 rarely vertically striated; tf-jlllf is present on all the crystals 

 and sometimes prominent. Its faces are bright and usually 

 marked by concentric triangles which represent oscillations in 

 the zone of trapezohedrons; s\321] is present on many of the 

 crystals; n\211\ occurs on every crystal and is often rather 

 prominent; m\Sll\ and ^-j411} are subordinate forms present 

 on about half the crystals; m\311\ is the more frequent of 

 the two and usually the larger; SJ610J and 0\ 430 \ are the 

 only pyritohedrons in addition to {210}. They are narrow and 

 unimportant forms. 



Each of the new forms is present on several crystals and 

 they are well established by measurements. <£|12*9'lj is in a 

 vertical zone with {430}. pjTO'7 1\ is near j 12-9*1 } in position 

 but is sharply defined. Tj8'10'5 is a negative diploid in the 

 vertical zone with [210: 211: 213] and hence only one measure- 

 ment was necessary for its identification. #{371} is present 

 on several crystals. Its faces are striated and apparently there 

 is a (370) face. Measurements in the cube and pyritohedron 

 zone give an image for the (370) position, but in the [371: 3-71] 

 zone there were multiple images but no definite one for (370). 

 This example, it is thought, shows an advantage of one-circle 

 measurements over two-circle measurements. 



