BY W. H. CLEMKS, 15. A.. li.SC. 1!> 



constituents are very few. Eunning through the boulders 

 oh the sides of Mt. Hazard are to be found narrow veins 

 of niicrogranite, a very fine-grained variety composed of 

 felspar, biotite and quartz. On the northern side of the 

 bay also occurred a highly porphyritic granite with large 

 crystals of felspar (orthoclase ?), also quartz, biotite and 

 muscovite. 



Numerous quartz veins trav»'rsi-<i the rock in a more or 

 less north and south direction, and varied considerably in 

 size. They varied also in colour from rose to white, and 

 there were numerous nests of rock crystals. There was 

 no evidence of the greisenised zone, carrying fin, found at 

 the northern end of Schoutcn Main. 



At intervals along the south side of the bay are 

 parallel dykes of dark rock, running approximately north 

 and south. This rock has previously been referred to by 

 Dr. INlilligau, who tliought that it waii greenstone, and 

 certainly it somewhat resembles diabase or dolerite to the 

 naked eve. But microscopically it is resolvable into a 

 combination of plagioclase, fels])ar, and hornblende, and 

 is theiefore a diorite. Some biotite is also present. The 

 felspars in lath-shaped sections exhibit both albite and 

 Carlsbad twinning, and ti'om the extinction angles belong- 

 to the oJigoclase-andesinc series. The biotite where not 

 chloritised is brown in colour. The honiblendc is irregu- 

 lar in form and green. It is mostly chloritised to some ex- 

 tent, during which process iron oxide has separated out 

 abundantlv. Diorite is a rock which is met with in more 

 than one form of occurrence. It may exist in dyke form, 

 or as a separate rock mass, or finally as a facie? of granite. 

 Tho structure of the present rock is consonant with its 

 occurrence either as a faciei or a dyke. Evidently it has 

 genetic connection with the granite rock of Frevcinet 

 Peninsula. In one vein close to the waters edge large 

 crystals of felspar were to be seen embedded in the diorite, 

 whicn thei-e appeared more grey in colour. I was not able 

 to examine it closer owing to its position and the lack of 

 time, but it appeared as if some ab.sorption of the con- 

 stituents of the granite had taken place, leading one al- 

 most to suppose that the dyke theoiy was more probable, 

 but there is not sufficient data to dogmatise about the mat- 

 ter. They certainly appear to be xenocrysts rather than 

 phenociysts. 



Most of the hills appear as great boss-like masses with 

 rounded surfaces, curiously streaked by the descending 

 waters charged with mineral matter. These hills descend 

 right into the sea. with little or no foreshore. Along the 



