474 H. S. JEVONS, H. I. JENSEN, T. G. TAYLOR AND C. A. SUSSMILCH. 



Minerals present. Stated in order of decreasing abund- 

 ance, the minerals present, and their proportions by weight 

 after allowance for decomposition, are as follows:— 



Rosiival Method. 



Calculated from 



By weight as 



Corrected for 



Analysis. 





measured. 



decomposition. 



f Plagioclase 



38'i 



Felspar 29*2 



32'8 



I Orthoclase 



VI 



Augite 32*0 



31*4 



Augite 



30*4 



Olivine 11*5 



17-4 



Olivine 



14*2 



Serpentine 8*6 



... 



Biotite 



11-5 



Biotite 12*0 



11*8 



(Ilmenite 



3*2 



Iron ores 6*6 



6*5 



1 Magnetite 



•5 



Shales 0*1 



0*1 



Apatite 



1*0 











100*0 



100*0 



100*0 



The augite is purplish brown in colour, and includes much 

 magnetite in minute octahedra. 



The labraclorite occurs in tabular habit, giving mainly 

 lath-shaped sections. It is zoned, but all of it appears to 

 have a refractive index (R. I) well above that of balsam. 



The olivine phenoerysts are numerous, and are nearly 

 idiomorphic. They are free from inclusions of iron ores or 

 apatite except on the edges, and they are decomposed to 

 an olive-green serpentine mostly only along cracks. 



The analcite is very rare in some parts of the slide, and 

 its presence does not seem in any way dependent on 

 decomposition, as it is often abundant in roughly rectangular 

 patches in parts where chloritisation and serpen tinisation 

 are not to be seen. 



A certain amount of carbonate of lime is present in the 

 rock, as was proved by testing it with hydrochloric acid 

 under the microscope. Strong effervescence was observed 

 particularly in the vicinity of hematite, leucoxene, and 

 visible patches of analcite. Staining with eosin, the gela- 



