green, the polarization colours not brilliant. There is also, very 

 rarely, a colourless mineral in hexagonal prisms which appears to 

 be either apatite or nepheline. Forms a hill at the south end of 

 peninsula in Akaroa Harbour. Haast, Geol. of Canterbury, p. 

 '6U, (Granitoid Trachyte). 



7'ekoa, Amuri Co. — A fine grained, pale, pinkish-brown rock 

 with black prisms of augite. Section : composed of orthoclase, 

 plagioclase, augite, and a little hornblende. There is no quartz. 

 The felspars average -10 inch : the orthoclase is subordinate to 

 the plagioclase. The augites go up to -0.3 in length ; they are 

 green and mostly altered. The hornblendes go to -08 in length, 

 and are brown or green, sometimes actinolitic and probably 

 secondary after augite. Magnetite and hajmatite are accessories. 

 From a spur of Hurinui Peak, running to the Mandamus River. 

 Haast, Rep. Geol. Explorations 1870-1, pp.30 and 46, Section 17 

 (Diorite); also Geol. of Canterbury, p. 285. Hutton, Rep. Geol. 



ORTHOPHYRE QROUP. 



(Felsite in part.) 



Microgranitic compounds of orthoclase with some plagioclase, 

 hornblende or biotite, and often quartz. Sometimes with porphy- 

 ritic crystals of felspar, hornblende, or biotite. None as yet 

 described from New Zealand. 



TRACHYTE QROUP. 



Trachytic rocks composed of a semicrystalline ground-mass with 

 felspar microlites, containing porphyritic crystals of sanidine, and 

 usually plagioclase, with hornblende or mica, or occasionaly augite 

 or enstatite. 



HORVBLENDE Tr VCIIYTE. 



Lyttelton — Greenish-grey rocks with glistening lustre, often 

 ^esicular, and containing a few porphyiitic crystals of felsj^.ir and 

 long, narrow, prisms of hornblende. S.(t. about 2-44. Section: 

 ihe ground-mass is very abund.mt, microlitic, \\ith felspar micro- 

 lites and plates from -00^ to "01 in breadth, vMth gianule., of 

 niagiietite and infiltrations of chlorite F!n\iou -.tiuctuie is 

 puleiit The porphyritic minerals .ue >nn. lini' j 1 i^'im 1 im\ .ind 

 '"'Miblende. The sanidine is in carKb.uK .>i nirnji n md up 

 ' ' 12 in length. The plagioclase goes u}. '.. \\ u\ . : ,tli, mhih- 

 '_ '-subordinate to, sometimes predoimn >nt .>\m tl..- ^ i-ndine. 



- d^ there are some nncrolites in the felspai s. There is a little 

 Fornix dykes on the Lyttelton and Sumner Roiid. Haast, 



