BY W. N. BENSON. 235 



it becomes three-quarters of a mile wide and contains much 

 gabbro. This belt occupies an opening between the jasper-hills 

 to the east and the Burindi(?) tuffs to the west. Its floor is 

 thinly covered with Tertiary(?) auriferous drift. The serpentine 

 and gabbro are a good deal altered, some quartz-veins have been 

 developed, and, in places, the gabbro is impregnated with pyrites. 

 About half a mile east of the old station-building is a most inter- 

 esting occurrence of chromite.* A circular area, roughly five 

 yards in diameter, is full of spherical segregations of very minute 

 chromite-cubes, set in a matrix of green chlorite and serpentine 

 with the chromiferous chlorite kammererite (Seel, Pt. iii. p.681). 

 On either side of this is a bar of amphibolite with very interest- 

 ing characteristics. (See descriptions of M.B. 189 and 186, 1, 

 Pt. iii., p.680). 



West of the serpentine is a bar of the usual serpentine-gossan, 

 which may be traced for some distance to the north. The belt 

 widens in this direction. Along its western side, schistose 

 serpentine is the predominant rock, with a thin "gossany" 

 margin, but, to the east, gabbro predominates, with bars of 

 schistose serpentine, and massive, or poikilitic bastite-serpentine. 

 This forms a great bulge to the east, and is bordered by the 

 jasper-hills. Its well matured surface slopes gradually eastward 

 to the Forrest Creek System. Northward, the area slopes rapidly 

 down, into Little Plains Creek, which escapes through a gap in 

 the hard tuff ridge to the west. Here is an interesting- 

 igneous complex of gabbro and serpentine worthy of further 

 study. The northern end of the mass is mostly massive bastite- 

 serpentine, with a brown weathering surface and marked relief. 

 The western side and southern portion are schistose, often with 

 large massive kernels perhaps two yards in diameter, while 

 within the mass are bands of massive and schistose serpentine. 

 The eucrite-gabbro and anorthosite [the "diorite" of Anderson(12)] 

 is largely gneissic (a fluxional structure having been impressed 

 upon it during consolidation), and has been altered mineralogi- 



* The Mineralogical Museum in the University of Ziirich contains an 

 analogous specimen from the Ural Mountains. 



