

ANDREWS : LIMESTONES OF THE FIJI ISLANDS. 41 



3. Munia. Specific gravity, 2.70. Taken from an andesite agglomer- 

 ate. Vesicular to cellular lava. Phenocrysts of plagioclase twinned on 

 albite type. Shows the " felt-like base." The felspar is much decom- 

 posed and the magnetite is well developed. 



4. Totoya. Specific gravity, 2.7. Sample from lava flow. This is 

 an andesite, much decomposed. Rock generally green, owing to decom- 

 position of augitic ground-mass into viridite. The felspar of the first 

 generation shows advanced kaolinization, and great abundance of lath- 

 shaped crystals of felspar. 



5. Munia. Specific gravity, 2.55. Specimen from lava agglomerate. 

 A cellular andesite lava. Iu section, shows a few pj-roxenes polarizing 

 in high colors, also plagioclase idiomorphs in a fine " andesite " base. 

 Zonal structure is found in the felspars and spherulitic structures are 

 common. 



6. Taviuni. Specific gravity, 2.66. Vesicular lava. Described more 

 fully later. A fine-grained black rock. Yields in section phenocrysts 

 of plagioclase set in a base of closely packed lath-shaped felspars and 

 the " felt-like " material common in andesites. Magnetite is common, 

 and also olivine or pyroxene. 



7. Singatoka River. Specific gravity, 2.71. Porphyrite in agglomer- 

 ate form. Large greenish plagioclase crystals in brown base contain- 

 ing second growth of minute felspar crystals. 



8. Levuka. Specific gravity, 2.8. Reddish andesite with porphyritic 

 development of green augite showing perfect idiomorphic contours. 

 Felspars of first generation much decomposed and corroded in the 

 andesite magma. This felspar occurs in nests. Zonal structure well 

 observed in felspars. Spherulites present as well as much magnetite. 

 Abundance of pyroxene decomposition products. 



9. Totoya. Specific gravity, 2.7. A greenish augite-andesite. Similar 

 to Xo. 4, but not so decomposed. Shows well-developed plagioclase 

 crystals in fine base with scattered magnetite as fairly large grains or 

 well-distributed specks. Second crop of lath-shaped felspar crystals. 

 Augites and pyroxene phenocrysts, the former showing zonal structure 

 at times. Fair examples of spherulites. 



10. Mba Vatu. Specific gravity, 2.85. Selected from tongue of 

 compact reddish andesite lava, with glistening felspar crystals. Shows 

 in section well-defined plagioclase crystals and phenocrysts of augite 

 with the usual accompaniment of lath-shaped felspars. This rock 

 exhibits the " felt-like base structure " with great development of 

 magnetite specks. Twinned augites occur. 





