BY W. a. WOOLNOUGH. 803 



The presence and mode of occurrence of quartz and calcite 

 have been noted above. (Plate Ixix., fig. 5.) 



Analysis by A. B. Walkom. 



Per cent. 



SiOa 39-49 



AI2O3 15-97 



Fe^Og 7-09 



FeO 2-59 



MgO 1-97 



CaO 31-60 



K2O absent 



Na.^O 0-12 



H2O- 0-04 



H2O + 0-13 



TiO.2 1-01 



CO2 0-17 



MnO.., 0-32 



Total 100-50 



No. 6 is an even-grained rock of about 1 mm. to 1-5 mm. grain- 

 size. In handspecimen the rock is dioritic in appearance, but 

 is very much too high in specific gravity for any eruptive rock. 

 The only mineral very clearly recognisable is a black pyroxene 

 with marked lustre mottling. Small amounts of whitish minerals 

 are also present, and, on close examination, the resinous garnet 

 intergrown with the pyroxene can be seen. 



Under the microscope the texture is diablastic, the rock con- 

 sisting chiefly of a green pyroxene approaching fassaite. This is 

 diablastically intergrown with pinkish garnet slightly different 

 in appearance from that so abundant in the last rock described. 

 A small amount of colourless zoisite also enters into the diablastic 

 intergrowths. Some of it is quite clear, some altered into cloudy 

 radial aggregates of fine fibrous mineral. There is a very little 

 mica(phlogopite), and a small amount of secondary calcite (Plate 

 Ixix., fig.6). 



No. 7. In hand.specimen this rock does not differ essentially 

 from N0.6, except that large isolated masses of red garnet occur 

 sporadically through it. 



