(•02 to -04), pale greenish augite (-02 to -06) and enstatite (-02 to 

 ■03). The last is idiomorphic, pleochroic, a and /3 yellow-brown 

 to reddish-brown, y bluish-green. From the southern and western 

 slopes of the mountain. 



Lake Taupo. — Black sub-vitreous rocks with abundant yellowish 

 felspars and less conspicuous pyroxenes. Section : Ground-mass 

 abundant, vitreous, a brown or dark brown glass with either 

 scattered magnetite granules, or scattered colourless crystallites 

 in bands and clusters. The porphyritic minerals are plagioclase, 

 augite, enstatite and magnetite. The plagioclase is not zoned, 

 but sometimes pseudo-schillerised, and up to -15 in length. The 

 augite is yellowish-green, up to -03 in length. The enstatite is 

 more abundant than the augite, goes to -05 in length, pleochroic, 

 changing from brownish-yellow to bluish-green. Fragments 

 picked up on the north shore of the lake. 



Mount Horohoro, Rotorua. — A black sub-vitreous rock with 

 scattered yellowish felspars. S.G. 2-545. Section : Ground-mass 

 abundant, vitreous, a brown glass with scattered magnetite grains 

 and minute felspar microlites shewing fluxion. The porphyritic 

 minerals are plagioclase, augite, enstatite and magnetite. The 

 plagioclase crystals go to -04, they are not much twinned. Tlie 

 augite is pale greenish, in small quantity, up to -04. The enstatite 

 ^ pleochroic changing from reddish-brown to bluish-greeiu 

 Hochstetter, New Zealand, p. 403. 



White Island, Bay of Plenty. — A brownish-grey rough rock with 

 abundant white felspars. Section : Ground-mass moderate, crystal- 

 Iitic, globulitic, with magnetite and haematite. The porphyritic 

 minerals are plagioclase, augite, enstatite and magnetite. The 

 plagioclase goes to -15. The augite is greenish. The enstatite is 

 usually about -04 in length, slightly pleochroic, changing from 

 yellowish-brown to yellowish-green. The augite and enstatite 

 sometimes form intergrowths. Hector, Trans. N.Z. Institute, 



Thames Gold-fields.— \. Greenish-black, semi-vitreous rocks with 

 " ■ " "■ S.G. 2-72. Section: 



, „, „ glass crowded with 



small felspar laths and with rather large magnetite grains. The 

 "^ "" ' " srals are plagioclase, augite, enstatite or protobastitfr 



The plagioclase is generally clear and zoned, often 

 ary twins, goes up to -Oi. Augite is not abundant, pale 



•o-porphyritio, the clustres -OS in diameter. The enstatite 



Octtis.onally the axiar plane lies i 

 Cise the mineral is protobastite. T 



