130 F. W. HUTTON. 



by a brown decomposition product. The porpliyritic minerals are 

 plagioclase and hornblende. The plagioclase crystals are from -02 

 to -04 in length, strongly zoned with negative crystals, and are 

 not much decomposed. The hornblende is scarce and is mostly 

 decomposed into an opacite, sometimes with chlorite ; it is brown 

 and the angle c :y=12°. Magnetite is in rather large grains 

 decomposing into limonite. From the island in Omaru Bay. 

 Hector, Rept. Geol. Explorations, 1870-1, p. 97, diagram iv. 



AUGITE PORPHYRITE. 



Enfield near Oamarw— Dark grey or blackish compact rocks, 

 decomposing reddish-brown with white spots. S.G. 2-64 to 2-67. 

 Section : Granular, composed of plagioclase, augite and ilmenite, 

 with perhaps a little base. The plagioclase is in laths, from -01 

 to -04 in length. The augite is in grains about -002 to -003 in 

 diameter, partly gregaritic and semi-ophitic. Secondary minerals 

 are leucoxene, haematite and sometimes a little chlorite. Hutton, 

 Trans. N.Z. Inst., Vol. xix., p. 419. 



Harts Coal Mine, Malvern Hills, Seltvyn Co.— A greenish-black 

 compact rock, decomposing reddish-brown. S.G. 2-71. Section: 

 Granular; composed of plagioclase augite and ilmenite. The 

 plagioclase is in laths -01 to -02 in length. The augite is in grains 

 •004 to -01 in diameter. Secondary minerals are brownish-green 

 <!hlorite, a colourless aggregate with brilliant polarization colours, 

 leucoxene and white pyrites. Haast, Reports Geol. Explorations, 



Olivine Porphyrite. 



Moeraki Peninsula, Otago — A dark grey, rather coarse grained 

 rock. S.G. 2-77. Section : Microgranitic ; composed of plagio- 

 clase, augite, olivine, and ilmenite. The plagioclase is usually 

 between -01 and -02 in length, rarely -08. The augite is brownish- 

 yellow, not abundant, granulitic, or glomero-porphyritic in places ; 

 the grains about -01 in diameter. Olivine is rare. Leucoxene 



ily. Hi 

 N.Z. Institute, Vol. xi: 

 ations, 1886-7, p. 839. 



Chloritic Porpiiryite. 



Reefton, Inangahua Co. — A soft greenish-grey, compact rock, 

 with dark green, almost black, shining patches of chlorite. S.G. 

 2-73. Section : Microgranitic, composed chiefly of plagioclase 

 laths, from -02 to -04 in length, and chlorite. Other secondary 

 minerals are calcite, leucoxene (?) and pyrites. The plagioclase is 

 much decomposed. The chlorite is bright green and feebly 

 pleochroic ; it sometimes forms pseudomorphs after augite, but 

 usually it k in irregular masses. From Specimen Hill Mine at 

 Boatmans, 



