452 



PROCEEDINGS OF THE ACADEMY OF 



[Part III 



grains exhibit mesh structure and contain residual olivine, indi- 

 cating that the parent rocks were largely peridotites of the type 



Fig. 1. 



Fig. 2. 



Fig. 3. 



Fig. 4. 



Fig. 1. Serpentinization proceeding along cracks in olivine. Jenkin's Mine. 

 Ordinary light, x 15. Fig. 2. Chromite, "birdseye ore," in more or less ser- 

 pentinized olivine. Note rounded form of chromite and serpentinized olivine 

 crystal in the chromite. Jenkin's Mine. Ordinary light, x 15. Fig. 3. Chro- 

 mite in fibrous williamsite. Line Pit. Polarized light, x 15. Fig. 4. Chro- 

 mite in williamsite. Note fractured character of the chromite. Line Pit, ordi- 

 nary light, X 15. 



