104 Transactions of the Royal Society of Victoria, 



tints of brown. These crystals do not lie in any definite 

 direction in the slice, although they form bands in it, thus 

 producing a schistose appearance. They are mostly short 

 and rather stout, prismatic crystals, three, six, or nine-sided, 

 and hemi-hedrally terminated. The dimensions of these 

 crystals are about the same as those last described. They 

 are, and especially the larger ones, much eroded and 

 cavernous, and include numerous particles of quartz. Tlie 

 crystals are pleochroic, the E ray being nearly colourless, 

 while the ray is a dark golden brown. These observa- 

 tions were further confirmed by an examination of a number 

 of these beautifully splendent crystals which I isolated by 

 means of h3^drofiuoric acid. The main mass of this rock is 

 composed of numerous grains of quartz, with a few small 

 grains of triclinic felspar. 



It seems to me that this rock represents a portion of schist 

 in which the bases have been converted into tourmaline, 

 with also an access of silica as quartz. 



The Muscovite granite at this contact varies much in 

 grain. Id some parts, the constituent minerals are up to an 

 inch across, while as to others, all that can be said is, that it 

 is slightl}^ coarser than that of the average rocks of the 

 neighbourhood. 



I separated samples of the felsjDar, mica, and quartz for 

 examination. 



The felspar is yellowish in colour. In places, it is some- 

 what intergrowii with quartz, after the manner of " graphic 

 granite." Under the pocket lens it also shows those 

 irregular veinlets of a second felspar on OP (001), and 



ooPgo (01 Oj, which indicate a microperthite. I found on 

 examining a thin slice prepared from the most perfect 

 cleavage (OP), that this felspar is a well-marked example, 

 the albite veins being very characteristic, as well as the 

 twinned structure of the microcline, which is the form of 

 the potassa felspar. 



A slice from the less perfect cleavage ( go oo ) showed me 



also the familiar appearance of irregular veinlets of albite, 



traversino' the slice at anoies between 60° and 65° to the 



• 

 trace of the perfect cleavage. A second set of veinlets were 



also interposed in the plane OP, and which in places connected 



with the other series. The inclusions in this felspar are confined 



to grains of quartz, and rarely plates of muscovite. Through 



the kindness of Mr. J. C. Newbery, C.M.G., Mr. Jas. C. Fraser 



