LiVERSiDGE. — Analyses of a Bock Specimen from New Zealand. 505 



From wliicli it will appear that the enclosed fragment cannot be regarded 

 as quartz but rather as quartzite ; it is probably a portion of some sedimen- 

 tary rock which has been metamorphosed by the action of the fluid basalt. 



Taranaldte/'' — Taranaki. 



Aet. LXXVIII. — Analyses of a Rock Specimen from New Zealand, sJioioing 

 the Junction between Granite and Slate. By Archibald Liversidge, 

 Professor of Geology and Mineralogy in the University of Sydney. 

 Communicated by Professor Hutton. 



[Bead before the Otago Institute, 8th November, 1877.] 

 I AM indebted to the kindness of Capt. Hutton, F.G.S., Director of the 

 Museum, Dunedin, for an opportunity to examine this most interesting 

 specimen ; although the dimensions of the specimen were originally only 

 about one and a-half inches by one and three-quarters, and perhaps one 

 inch in thickness, yet one-half of the specimen consisted of a fine-grained 

 greenish grey-coloured slate, while the remaining portion was made up of a 

 nearly white granite, possessing well-defined characteristics ; the crystals 

 of orthoclase felspar are fairly well-defined and exhibit comparatively large 

 cleavage planes ; the mica and quartz are also distinctly developed ; even 

 in so small a fragment the granite does not merge so insensibly into the 

 slate as we might naturally expect, but the two are joined along a com- 

 paratively well-defined hne of junction. 



The following analytical results, which are each the mean of two 

 analyses, show the differences in the chemical composition between the 

 granite and slate portions of the specimen. 



Analysis of the Granite. 

 Moisture driven off at 105° C. 

 Silica . . 

 Alumina 

 Iron sesquioxide 



,, protoxide .. 

 Phosphoric acid 

 Manganese protoxide 

 Lime . . 

 Magnesia 

 Potash 

 Soda . . 



Carbonic acid . . 

 Undetermined constituents and loss 



Specific gravity zz. 2'619. 





.287 





. 65-006 





. 17-371 





. 3-237 





•872 





. absent 





•393 





. 2-145 





•725 





. 3-294 





. 3-809 





traces 





. 1-861 





100-000 





Eep. N.Z. Exh., 1865, p. 423. 



n2 



