482 Transactions. — Geology. 



fectly fresh beyond a certain amount of reddish weathered 

 crust. It contains grains of chromite and occasionally small 

 crystals of diopside. 



To the west of the dunite no rocks are to be seen in situ, 

 but huge boulders of granulite and hornblende schist form the 

 beach, and probably indicate that these rocks succeed the 

 dunite in this direction. The granulite extends about a 

 quarter of a mile, and thereafter the beach consists for 

 400 yards of a light greenish-grey serpentine, with occasional 

 unaltered grains of olivine and some small veins of bowenite" 

 running through it. The serpentine gives place further on to 

 a beach of small pebbles, which is about 300 yards long. 

 Another mass of boulders is then found, and then another 

 small beach followed by granulite, much contorted, in situ. 



Among the boulders between the two beaches just men- 

 tioned were several boulders of hartzbergite, in which the 

 enstatite crystals stand out from the weathered surface. 

 They are sometimes 6 in. wide by as much as 2 in. broad. 



Another large boulder, weighing about 100 tons, was found 

 still further west than the granulite outcrop just described. 



So far as these geological indications afford evidence, it 

 seems probable that there is a large intrusion of dunite, some 

 part of which is changed to serpentine with veins of bowenite. 

 The hartzbergite appears to form another intrusion of smaller 

 size further west. 



These rocks were examined, with the following results : — 



Boioenite. 

 Hand-specimen clear transparent green, with a splintery 

 fracture and small opaque inclusions. Microscopically a 

 dense mesh of minute needles of colourless transparent ser- 

 pentine, occasional small unaltered cores of olivine, and 

 some grains of chromite. 



Dunite. (Plate XLVIL, fig. 1.) 



Hand-specimen pale olive-green rock, very dense, but 

 showing occasionally small crystals of chromite, some bright 

 cleavage-surfaces of diopside, and rounded larger grains of 

 olivine. 



Section. — The large olivine grains have undulose extinc- 

 tion, and are imbedded in a mass of olivine grains with 

 irregular-fractured boundaries evidently produced by crushing. 

 The whole structure is distinctly cataclastic. The diopside 

 is perfectly transparent, with good cleavage, and extinction 

 angle over 40°. Chromite barely transparent, with a brown 

 colour. No indication of serpentinisation of the olivine. 



* This mineral is mined from an adit 1,500 ft. above sea-level. 



