98 The Sedimentary, Metamorphic, 



In this are disregarded the amount of about 4 per cent, of 

 the rock, which is composed of epidote, magnesia-mica, and 

 ferric-hydrate. 



At this place there is a strong diabase dyke which crosses 

 the creek bed. The rock is much altered, most of the ground- 

 mass being serpentinised, and in the remainder chlorite has 

 been produced together with very numerous minute colour- 

 less rounded grains with rough surfaces, which are doubly 

 refracting, and which I think are epidote. The marked 

 features of this rock, as seen in a thin slice, are the amount of 

 unaltered augite in colourless or slightly reddish stout crystals, 

 and also the paucity of felspars. The augite obscures up to 

 angles of 36°. 



36. — At this place there appears a typical example of the 

 massive intrusive rocks of the district, and it is here that, I 

 think, must be placed the approximate contact boundary 

 between them and the metamorphic schists. 



For the purpose of comparison, I have made a quantita- 

 tive analysis of this rock, as well as examined it in a thin 

 slice. Under the microscope I find that it consists of the 

 following minerals, noted in their order of consolidation : — 

 Amphibol is in cavernous crystals, which are pleochroic in 

 shades of yellow to dark-green, the several rays being — c, 

 dark green ; > b, dull green : > a, yellow. The angle c : C 



I found in a section near to a Pec to be 26° 45', and 

 in a second, 29°. These angles are very high, but the 

 characteristic prismatic cleavage of very nearly 124° 

 30', and the strong pleochroism of the mineral, leaves 

 no doubt as to its being amphibol. Mica is in ragged 

 and crushed crystals, which in the slice become translucent 

 in dark shades of yellow ; macroscopically, they are black 

 and shining. It is dichroic in shades of yellow to nearly 

 black, and in places is intergrown with the amphibol. There 

 are traces of chloritisation of this mica, which commence at 

 the outside and follow the plates unequally. This mica 

 contrasts with that of the schists by its large percentage of 

 iron, which is evidenced by its more marked pleochroism ; 

 also by that of its resulting chlorite. It is probably, as is 

 that of the Noyang quartz-mica diorites, a Haughtonite: 



The felspars are all triclinia There may have been two 

 generations, if it is possible to draw such an inference from 

 the observation that some felspars are very much broken 

 and worn away at the sides, while others are tolerably well 



