only porphyritic crystals are plagioclase ; these are much altered 

 and tilled with a colourless aggregate shewing rather vivid polari- 

 zation colours. They are small, not more than -03 in length. 

 Some have infiltrations of a pale green chlorite, which is partly 

 isotropic, and partly shews low polarization colours. There are 

 also long colourless needles, generally with chloritic infiltrations ; 

 it is doubtful what these are as they rarely shew crystallographic 

 faces. Interbedded with the Maitai Slates in Brook Street Valley. 



2. Greenish-grey compact rocks, more or less mottled with pale 

 greenish-yellow epidote. S.G. 2-85 to 2-87. Section : Ground- 

 mass very abundant forming nearly the whole of the rock, partly 

 vitreous, partly felsitic ; some specimens with felspar microlites 

 (•006 in length) shewing evident fluxion ; others with microlites 

 and round balls of a chloritic mineral which is chiefly isotropic. 

 A small mosaic is generally apparent in the felsitic portion. 

 Magnetite, haematite and leucoxene are scattered in small specks 

 through the ground-mass. Felspar, in small fragments, is the 

 only porphyritic mineral, and even these are scarce and too much 

 altered for determination. Secondary epidote occurs in veins and 

 in masses. Associated with tuffs of a similar character at Mackay's 

 iiluff, on the south-west side of the syenite. McKay, Reports 

 <^eoI. Explorations, 1878-9, p. Ill (Serpentine). 



Haiiraki Gold-fields.— jy^rk or light greenish-grey rocks, some- 

 tunes speckled with white, and weathering to greyish-white. 

 Hutton, Pro. Australasian Association, 1888, p. 245. 



(A) With pseudomorphs after hornblende and Augite. 

 (Propylite.) 

 a. With quartz. 

 9 }k ^^^k greenish-grey rocks with greenish-white felspars. S.G. 

 x'l . .*° '^'^^' Section : Ground-mass abundant, crystallitic or 

 lelsitic without mosaic, colourless, with scattered magnetite 

 granules. The original porphyritic minerals still remaining are 

 quartz, plagioclase, and magnetite. Secondary minerals are 

 ^ff "^ ^^d magnetite after augite, and either chlorite or calcite 

 T J., "ornblende. The quartz is rare, allotriomorphic, from -01 

 fo 04 in diameter, corroded. Plagioclase crystals up to -06 in 

 length. On the shore north of Tararu Creek, 

 b. Without quartz. 

 i abundant, microlitic, or crystallitic, partly 



_ 2. Ground-n 



elsitic with scattered grains of magnetite. Original porphyritic 

 numerals are plagioclase and magnetite. Secondary minerals are 

 ca cite with opacite wreath after hornblende, and bluish-green 

 ^onte or bastite after augite. The felspars are small and much 

 oecomposed ; the chlorite is nearly isotropic, the bastite is pleo- 



