F W. Clarke — Some Nickel Ores from Oregon. 485 



to analysis, and also, through the kindness of Mr. J. S. Diller, 

 to careful microscopic study. The olivine separated from it by 

 Mr. Diller was analyzed as well, although the material was not 

 absolutely free from enstatite and chromite, and both analyses 

 are here presented together. 



Rock. Olivine. 



Ignition 441 -57 



Si0 2 41-43 42-81 



A1 2 -04 



Cr„0° s -76 -79 



Fe 2 O s 2-52 2-61 



Fe'O 6 25 7-20 



NiO -10 -26 



MnO none none 



CaO "55 none 



M^O 43-74 45-12 



99-80 99-36 



It will at once be seen from these data that the rock con- 

 tains nickel, and that the olivine separated from it contains 

 even a larger proportion. This fact suggests a probable source 

 of derivation for the nickel in the altered beds of ore, and this 

 view is maintained by the microscopic investigation. Con- 

 cerning the latter, Mr. Diller reports as follows, discussing 

 both the rock and the genthite. 



" The high specific gravity and dark yellowish green color 

 of the country rock with which the genthite is associated at 

 Kiddle, Oregon, at once suggests that it belongs to the perido- 

 tites, and such it is proved to be by investigation. It is a holo- 

 crystalline granular rock, composed essentially of olivine and 

 enstatite with a small percentage of accessory chromite and 

 magnetite. The olivine predominates, so that the enstatite 

 forms less than one-third of the mass. Both of these minerals 

 are clear and colorless, but may be readily distinguished by 

 their cleavage and optical properties. They are allotrio- 

 morphic, i. e. not bounded by crystallographic planes, and do 

 not contain prominent inclusions, excepting a few grains of 

 chromite and magnetite and fine ferritic dust. Notwithstand- 

 ing the comparatively fresh condition of the rock, to which, 

 according to Wadsworth, the name Saxonite may be applied, it 

 is completely permeated by a multitude of cracks filled with 

 serpentine resulting from alteration. Quartz also results from 

 the metasomatic changes in the saxonite, and wherever the 

 genthite occurs it is always associated with either quartz or 

 serpentine." 



" The genthite from Oregon varies in color from green to 

 pale apple or yellowish green in reflected light, and is compact 



