Gorge of the Selvn/n River, Malvern IliUs.— Greyish-green to 

 greenish-grey rocks, without porphyritic crystals. S.G. 2-96 to 

 3-65, Section ; Granular ; composed of white saussurite and pale 

 brownish-green augite, both allotriomorphic, the relative amount 

 varying, but perhaps, on the average in equal quantity. The 

 saussurite forms a net work in which lie the augite grains, usually 

 •01 in diameter, but sometimes -025 ; often broken, the parts 

 sometimes with similar orientation, but usually independent. 

 Secondary minerals are leucoxene and chlorite. Haast, Geol. 

 Canterbury, p. 276 (Diabase) ; Hutton and Gray, Trans. N.Z. 

 Inst., Vol. XX., p. 271. 



Olivine Basalt. 



Oamarn, Waitaki Co. — A black, compact, vitreous rock. S.G. 

 2-72. Section : Ground-mass vitreous, a pale smoky-brown glass 

 with numerous plagioclase laths, -025 in length, and scattered 

 grains of olivine -002 to -02 in diameter. Contains also greenish 

 spherulites which shew a fixed interference cross parallel to the 

 diagonals of the nicols. Partly decomposed into a yellow-brown 

 palagonite on the outside. It is a Magma basalt. Forms a breccia 

 with calcareous cement. Also a peripheral layer on dolerite bombs. 

 Hutton, Trans. N.Z. Ins., Vol. xix., p. 417 (Tachylyte). 



Geraldine. — A dark grey vesicular rock without porphyritic 

 minerals. Section : Ground-mass very abundant, microlitic, of 

 plagioclase laths, -007 in length, and grains of augite, -002 to -003 

 in diameter, and magnetite, without any glass. The porphyritic 

 minerals are augite and a little olivine, both colourless, and not 

 larger than -015 in length. Forms a hill at Waihi Bush. Haast, 

 Geol. Canterbury, p. 314. 



Hvjh Peak, JMvern Hills, Selvijn Co.— A grey rock full of 



abundant, microlit 



artly 



