154 



G. T. PEIOR. 



100-49 100-00 99-99 



Calculation of the "norm " gave the following- result : — 

 Quartz 29-88 



Orthoclase 



Albite 



Anorthite 



AUG;, . 



MgSiO., 

 (FeMn)SiO 

 Magnetite 

 Water 



27-80 

 81-44 

 3-06 

 1-68 

 0-20 

 1-06 

 0-93 

 4-43 



In the American classification the rock would be classed 

 under Liparose. 



A dark glassy rock (402) from Indulawane Hill, south of 

 Crossly's Store, is of more basic composition. Under the 

 microscope the rock shows small, well-shaped phenocrysts of 

 felspar in a glassy base crowded with niicroliths; magnetite 

 grains and pale-green augites are sparingly distributed. Of 

 the porphyritic felspars some show the minute twin-striations 

 characteristic of anorthoclase while others show Albite twin- 

 ning, with symmetrical extinctions about the twin-lamellas of 



