66 



NEW YORK STATE MUSEUM 



The graphite occurs as elongated, oval to irregular shaped flakes, 

 nearly all of which are parallel to the schistosity of the rock, fre- 

 quently interleaved and surrounded by mica and pyrite. The latter 

 mineral has clearly been introduced at two different periods. The 

 flakes very often bridge across the grains of quartz or feldspar. In 

 the crushing of such ores the attrition of the flake is likely to occur. 

 The cross-sections of the flakes, as seen in the microscopic slides 



Quantitative microscopic analyses of the Bly ores 





Eutoka 

 pit 



1 



pit 



2 

 pit 



Joan 

 pit 



" South 

 Side l pit 





No. 639 

 845 



No. 846 



No. 847 



No. 640 

 848 



No. 641 

 849 





Graph 

 Mica. 

 Feldsp 

 Quart 

 Pyrite 

 Total 



ite 



6.5 

 10.0 

 40.0 

 33.5 

 10.0 

 100.0 



6.5 

 10.8 

 64.2 

 10.8 



7.7 

 100.0 



5.5 

 11.5 

 57.0 

 14.5 

 11.5 

 100.0 



6.0 

 11.0 

 59.5 

 18.5 



5.0 

 100.0 



6.5 



z 



o 





10.8 



8 



ar 



27.5 







53.0 



o 





2.2 



< 





100.0 



8 







Si 



Species of 

 feldspar 



Andesine 

 oligoclase 



Andesine 

 micro cline 



Plagio- 

 clase 



Plagio- 

 clase 



Ortho- 

 clase 





Z 

 g a 





1 . 23 mm 



X 



1 . 44 mm 



1 . 50 mm 



.90 mm 



1 . 20 mm 



X 



1.37 mm 



1 . 84 mm 



.80 mm 



.73 mm 



X 



1 . 25 mm 



1 . 50 mm 



.65 mm 



.85 mm 



X 



1 . 35 mm 



2 . 00 mm 

 .65 mm 



.94 mm 



fa 





X 



1 . 41 mm 

 1 . 80 mm 



s 





.75 mm 











a 



X 

 H 



fa 

 O 



c/) C 



5 5 



Average 



. 029 mm 

 . 060 mm 

 .018 mm 



.022 mm 

 . 036 mm 

 .012 mm 



.028 mm 

 . 066 mm 

 . 006 mm 



. 024 mm 

 .041 mm 

 .019 mm 



.025 mm 

 . 043 mm 



a 





.012 mm 









prepared from specimens, reveal the fact that dynamic disturbances 

 have frayed them into forms resembling horsetails. Analyses of 

 four samples from various pits are reported by Bastin as running 

 6.4, 6.6, 6.2 and 8.8 per cent of graphitic carbon. "An analysis of 

 a composite sample selected in 1904 to represent as nearly as might 

 be the general run of the property showed about 5 per cent of 

 graphitic carbon." 1 The ore from the " South Side " pit differs 

 from the others in that the quartz is more abundant than the feld- 



1 Bastin, E. S., Resources, 1908, 2:728. 



