Rocks of the Hoivqua River. 51 



■Gap, especially in' the present bad state of repair of the road. In 

 .general it occurs at intervals alono; the western margin of the large 

 diabase area, and round the edges of the smaller one. Though 

 .son:ietimes massive it is generally schistose and iron-stained. Tlie 

 ^crushed margins of the diabase appear to have been most favour- 

 able for its development. At Cameron's Creek about a mile and 

 a-half south of Lick Hole Creek, a schistose talc rock with very 

 little iron stain appeared to be slightly auriferous. Some pros- 

 pectors at work during the writer's examination obtained a fair 

 prospect of very fine gold fro^m a trench entirely in this rock. 



(d) Serpenti?ie and Chrysotile. 



Three outcrops of serpentine, all of fairly limited extent, have 

 been noted. The largest occurs on a ridge about half a mile south 

 of Lick Hole Creek, in the track to Cameron's Creek. It isi of the 

 usual dark green type, and varies from massive to schistose. 

 Isolated grains of chromite have been detected in it, but no quan- 

 tity of this mineral has yet been found, nor has any corundum 

 been observed in this district, as in the case of the Dolodrook and 

 Heathcote regions. A thin section shows the rock to be completely 

 .serpentinized, and it possesses the platy structure of antigorite, and 

 is, therefore, probably due to the alteration of a pyroxene rock. 



The second outcrop is about a mile south-east of Fry's, on 

 the western margin of the diabase; its extent is masked here by 

 much surface soil and hill slip material.. 



This outcrop is noteworthy, because it contains chrysotile asbes- 

 tos. The increased deanand for asbestos during the war, both locally 

 and abroad, has induced much searching after local supplies, and 

 this occurrence has been taken up by Mr. Fry Avitli a view to open- 

 ing it up to prove its worth. At the timei of my visit only shallow 

 'hillside cuts had been made. These revealed thin veins of chryso- 

 tile traversing the serpentine along numerous joints and slip 

 planes forming a network which at some of the intersections deve- 

 loped into knots or centres of chrysotile. All the material noted 

 was of a slip fibre type — that is, it consisted of somewhat over- 

 lapping fibres lying parallel to the joint and slickenside planes. 

 None of the cross-fibre type was observed. With regard to tlie 

 origin and development of chrysotile veins in serpentine, the sub- 

 ject has been discussed by Graham in Economic Geology. ^ His 

 inquiry leads him to favour the idea that the agents of change for 

 the Canadian occurrences were magmatic siliceous Avaters derived 

 "from neighbouring granitic intrusions. 



5a 



