DYKE-ROCKS RELATED TO B ANA KITE. 
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principal products into which the magma appears to have been differentiated in the 
recent lava-hows. If the FeO and Fe 2 0 3 are taken together, then no item in the two 
results, except that of the MgO, differs by more than 1 per cent. In these banakite- 
like dykes, too, occurs the basaltic hornblende which is so ubiquitous a mineral in the 
recent lavas. The ratio of Na 2 0 : K 2 0 is also nearly the same as in the younger rocks. 
Doubtfully to be referred to under the heading of banakite is the dyke-rock (566) 
intrusive in the crystalline limestone of the Northern Foothills at G 4 . It is a dark- 
greenish-gray speckled rock, showing to the naked eye no phenocrysts. Under the micro- 
scope it is seen to be microporphyritic, with numerous small, sharply-defined phenocrysts 
of purplish augite, green chloritic and serpentinous pseudomorphs (possibly after 
hornblende) and a few altered felspars. The ground-mass consists of altered felspar 
prisms with shreds of biotite and hornblende and sparingly scattered magnetite-grains. 
Of very similar character is the dyke (565) in the granite at e 6 above the head of 
Blue Glacier. 
The specimen (646) found by Lieut. Skelton in a moraine, ten miles beyond 
Cathedral Bocks, deserves mention here. It is a brownish-grey compact rock, 
conspicuously porphyritic, and showing to the naked eye small prismatic felspars and a 
few crystals of augite and hornblende. Under the microscope are seen phenocrysts of 
oligoclase (symmetrical extinctions of 10°) and sharply -defined, nearly-colourless, 
augites in a base of felspar-laths ; phenocrysts of basaltic hornblende are also sparingly 
distributed. The rock is altered, with development of much epidote in the phenocrysts 
of felspar and augite. 
