140 F. W. HUTTON. 



Forms masses between Karaka and Waiotahi Creeks. It is the 

 miocene dolerite of Mr. Cox, Rep. Geol. ExpL, 1882, p. 19. 



2. Greenish- or greyish-black rocks with greenish-white felspars 

 and black pyroxenes. S.G. 2-74 to 2-78. Section : Ground-mass 

 small, microlitic or crystallitic (longulitic), often different textures 

 in the same specimen, the glass colourless, with numerous felspar 

 laths and scattered, rather large grains of magnetite. The por- 

 phyritic minerals are plagioclase, augite, enstatite and magnetite. 

 The plagioclase goes to -04 in length, it is zoned and often much 

 decomposed. The augite is pale yellow, idiomorphic, from -02 to 

 •05 in length, often altered into a blue-green chlorite. The 

 enstatite is idiomorphic, from -03 to -06 in length, pleochroic, 

 changing from yellow-brown to bluish-green; sometimes inter- 

 ■ ' I augite, sometimes glomero-porphyritic. Often altered 



polarization colours. Apatite is i 

 enclosures in the pyroxenes. There is also sometimes pyrites. 

 From Karaka and Waiotahi Creeks. Button, Report Geol. Expl 

 1868-9, p. 20, (Dolerite); Hector, I.e., p. 40, Table of Analyses, 



^3. A greenish-black rock with abundant small felspars. S.G. 

 ^•73. Section : Ground-mass small, vitreous, a pale brown glass 

 crowded with small felspar plates and grains of magnetite, and 

 with chloritic infiltrations. The porphyritic minerals are plagio- 

 clase, augite, bastite (after enstatite) and magnetite. The plagio- 

 clase IS zoned, goes up to 06 in length. The augite is pale greenish- 

 yellow and up to -04. The bastite is idiomorphic pseudcmorps 

 after enstatite, an aggregate with maximum extinction parallel to 

 the cleavage ; it goes up to -03. Apatite is present a ' ^ '-"" 



m the pyroxenes. O*' — ' 



fiugite, pyrites, and i 



the Prince Imperial Mine. 



These three rocks form a series differing in the amount of 

 decomposition they have undergone, and passing into the Chloritic 

 Andesites from the same district. 



Pnponga Point, Mannkau Harbour.— \. A brownish-grey rock 

 with scattered felspars and occasional pyroxenes. S.G. 2-52. 

 Section: Ground-mass moderate, crystallitic, the glass brown; 

 crowded with microlites and small crystals of felspar. The por- 

 phyritic minerals are plagioclase, augite, enstatite and magnetite. 

 Ihe plagioclase goes to -08 in length. The augite is pale greenish, 

 to 04. The enstatite allotriomorphic, pleochroic, changing from 

 reddish-brown to bluish-green, up to -03 in breadth, generally 

 antergrown with augite. 



