532 



THE CONTINENTAL ORIGIN OF FIJI, II., 



parting parallel to the clinopinacoid. This latter appears to be 

 of the nature of a solution-plane, since it is marked by the 

 development of dusty magnetite and plate-like bodies. Tt is not 

 a very constant feature, and is observable in only a few sections. 

 The refractive index and double refraction appear to be about 

 normal for basaltic hornblende. The highest extinction angle in 

 the prism zone is 12*'\ Pleochroism is very strong, the scheme 

 being : a = straw -yellow, 

 b = clove-brown. 

 C = dark greenish-brown. 

 The absorption being sensibly : a<b = f. 



Between crossed nicols the ordinary orthopinacoidal twinning 

 is exhibited by most sections. In some it is 

 simple in character, in others twin lamellae are 

 interposed between the two main portions. In 

 one vertical section [parallel to (010)] it appears 

 that two individuals are somewhat irregularly 

 intergrown in twinned position (see text-fig.). 



In convergent light, sections perpendicular to 

 the prism zone show the emergence of a positive 

 l)isectrix slightly oblique to the plane of the 

 section. 



In addition to magnetite and apatite, neither of them very 

 abundant, the hornblende contains liquid-inclusions with moving 

 bubbles The plate-like bodies referred to above are partly 

 arran<j:ed parallel to the clinopinacoid, partly irregularly; in the 

 former case they recall the " Schiller " structure of certain 

 hypersthenes. 



The pyroxene of this rock is almost colourless augite. It 

 is far less abundant than hornblende. It differs slightly 

 from the augite in the rocks hitherto described. The sections 

 are sharply idiomorphic. In the vertical zone they are bounded 

 by -j 100 [■ , -\ 010 }■ , and <| 110 [> about equally developed, so 

 that cross sections are almost perfect octagons ; along the 

 vertical axis they are terminated by pyramid faces. The 

 colour in ordinary light is ver}- light greenish-yellow, the refractive 



