52 E. 0. Teale : 



Twelvetrees,^" in describing the asbestos occurrence in serpen- 

 tine at Anderson's Creek, near Beaconsfield, I'asmania, also pos- 

 tulates a causal connection of the origin of the asbestos with a 

 neighbouring granitic intrusion. 



At Heathcote and Howqua the rocks have certainly been invaded 

 by siliceous solutions, and in each case granitic intrusions are 

 present in close proximity. It is reasonable, therefore, to suggest 

 at any rate that the vicinity of an acid magna may have provided 

 conditions which were favourable for the remarkable selective' 

 metasomatic and other changes, which were wrought along favour- 

 able lines and zones in both of tliese areas. At Howqua, grano-dio- 

 rite occurs on the southern slopes of Mount Buller, and a mass of 

 dacite porphyry of related age is actually in contact with the 

 diabase between the Howqua and Timbertop. 



{e) Mhieralizatioii of the Diabase. 



Another phase in the alteration of the diabase is shown by the 

 siliceous sulphide occurrence at the abandoned gold mine, about a 

 mile south-east of Fry's. Ihe occurrence is an interesting one, and 

 it has been known under different names during its chequered 

 career as a mining venture, but perhaps its best known title is the 

 Great Rand Mine. No accurate survey of this deposit has been i 

 made so far as the writer is aware, but like many sulphide occur- 

 rences its shape would appear to be irregularly lenticular, consist- 

 ing of a metasamotic replacement in a fracture zone. The quartz 

 is tough, and very finely granular, and the sulphides are abun- 

 dantly distributed through it. Iron sulphides, pyrite and pyrrho- 

 tite, predominate, but, galena, sphalerite, chalcopyrite and ar- 

 senopyrite were noted in small quantity. During my last visit to 

 this region, the mine was being tested by a small syndicate, Avith 

 the view to determining whether it was possible to treat the ore 

 2orofitably. The deposit was systematically sampled under the 

 direction of Mr. W. A. T. Davis, of Melbourne, and through the 

 courtesy of Mr. Cottingham, one of the syndicate, I was able to 

 note hurriedly the character of the deposit, as far' asi the old work- 

 ings would i>ermit. Ihese reveal a mineralized zone about 300 feet 

 long, in a north and south direction, by nearly 200 feet from east 

 to west. 



The mineralization is irregular, and sulphides are found in 

 varying quantities throughout the rock from considerable masses 

 to a mere impregnation. The examination was too short to deter- 



