146 F. W. HUTTON. 



a little chlorite and serpentine, and radiating tufts of a zeolite 

 Hector, Rep. Geol. Expl. 1870-1, p. 49, Sect. 3 ; Haast, I.e. 

 1871-2, pp. 26 and 73, Geol. of Canterbury, p. 301 ; Hutton, 

 Rep. Geol; Expl. 1872-3, p. 42 ; Daintree, Trans. N.Z. Inst., Vol. 

 VII., p. 459. 



Enstatite Gabbro. 

 (Norite.) 



Mata River, Waiapu District.— A coarse grained rock made up 

 of white felspar and dark brown pyroxenes. S.G. 2-80. Section : 

 The felspars all give broad sections ; they rarely shew polysynthetic 

 twinning, but cleavage flakes in convergent polarised liglit shew 

 an optic axis sometimes on the edge of the field, sometimes well 

 inside it ;* the former are bytownite, the latter anorthite. They 

 are rarely under -04 in length and sometimes -25 x "25 inch. The 

 pyroxenes are all allotriomorphic, and go up to -10 in length. The 

 commonest is diallage, but augite and bastite are also present. 

 The bastite is pleochroic changing from yellow-green to blue-green: 

 cleavage flakes shew a negative bisectrix. Secondary minerals 

 chlorite, slightly pleochroic, and a small quantity of pyrites. 

 Boulders in the river bed. 



Saussuritic Gabbro. 

 (Euphotide.) 



Bun Mountain, Nelson.— A coarse grained rock composed of 

 saussurite, pyroxene, and some hornblende, in crystals up to -30 x 

 •40. Section : The pyroxenes are diallage and enstatite ; the first 

 is yellowish, not pleochroic, and cleavage flakes shew an optic axis: 

 the second is pleochroic, changing from reddish-yellow to blue-green. 

 The hornblende is also pleochroic, changing from yellow-green to 

 blue-green ; the angle 7:0=19". Secondary minerals are a little 

 chlorite and epidote. Forms a dyke in serpentine. Hochstetter, 

 Lectures on the Geology of New Zealand, p. 94 (Gabbro), and 

 * New Zealand,' p. 475 (Diallage Rock) ; Hutton, Trans. N.2. 

 Inst., Vol. XIX., p. 412. 



Formerly I confused the ferro-magnesian minerals together and 

 took them to be anthophyllite ; a second examination of the rock 

 has shewn me my error. 



Microgranitic compounds of plagioclase with augite, enstatite, 

 olivine and occasionally hornblende. The plagioclase is in laths. 

 Sometimes with porphyritic minerals similar to those forming the 

 ground-mass. Rarely meteoric. 



Hornblende Dolerite. 



Lyell, Buller Co. — A compact, greyish-black rock, with scat 

 porphyritic crystals of black augite and greenish olivine. 



