104 The Sedimentary, Metamorphie, 



in which the albite veins were more strongly formed than 

 elsewhere, a false proportion between the two felspars may- 

 seem to be indicated. 



Still further up Watts Creek from the contact I found 

 some interesting massive crystalline-granular rocks, which 

 are worth notice as being of a type which is occasionally, 

 though rarely, met with in the intrusive areas of this district. 

 The rock is exceedingly tough, and difficult to prepare as a 

 thin slice. Under the microscope I found it to be composed 

 of felspar and amphibol, with a little reddish-brown mica 

 and quartz. The miqa appears to have been of the first 

 consolidation, but there is so little difference in the three 

 minerals that I cannot feel confident on this point. The 

 mica is reddish-brown in colour and not deep in tint, and it 

 is dichroic in shades of the same to colourless. It is largely 

 chloritised, and otherwise does not call for further notice. 



The amphibol is of a peculiar character. It occurs 

 broadly-bladed to fibrous. There are no defined crystals, 

 but masses, which, when cut across by the slice, show the 

 characteristic prismatic cleavage of amphibol on a minute 

 scale. When lying more or less in the plane of the slice 

 the long narrow blades rarely have the same direction, but 

 lie across each other and extend to different lengths. In 

 places the mineral forms bundles of long and very attenuated 

 prisms, which, extending to different lengths, give the mass 

 a ragged-ended appearance. This mineral is faintly 

 pleochroic, and the obscuration angles reach in the highest 

 measurements 18°. In places I have observed a mass 

 which, although fibrous, shows twinning, the composition 

 face of which crosses all the fibres, which reach as parts of 

 the same mass on each side. This suggests that the bladed 

 or fibrous structure has been superadded upon the original 

 condition of the mineral. There are no traces of the form 

 of augite in the masses of this mineral, and it can therefore 

 scarcely be a true uralite, to which it has much resemblance, 

 but more probably one of the amphibols similarly altered. 



The felspars are all triclinic, but very few show any well- 

 defined bounding planes. Their structure is very varied, 

 as well as compound. Some crystals are twinned according 

 to the Albite law, others according to this and also to the 

 Carlsbad law. The greater number have either portions in 

 which the lamellae differ in width from the others, or extend 

 only partly across the section. Perhaps half the individuals 

 in a slice are compounded according to the Pericline law, in 



