about equal in size, between -005 



forms the principal part of the rock. It is strongly pleochi 



allotriomorphic, up to -10 in length, sometimes actinolitic or con- 

 fusedly crystalline, and is probably altered augite. Apatite and 

 a small quantity of magnetite occur as inclusions in the biotite. 

 Hutton, Quar. Jour. Geol. Soc. of London, Vol. xliv., p. 745. 

 Chloritic Pyboxenite. 

 Martin's Bay, Fiord Co.— A soft, dark green, granular rock. 

 S.G. 2-96. Section : Composed of biotite and chlorite, in plates 



"^ 'r" ■ ■■ " 



yellow-bro 



short diagonal of the nicol, and blue-green whenlhey are parallel 

 to it. Some of the biotite is more altered than this and is quite 

 green in colour. The chlorite is blue-green and isotropic. 

 PICBITE GROUP. 



Granitic compounds of olivine, enstatite, augite, and sometimes 

 hornblende, with generally a little plagioclase, and often biotite. 

 Silica 46 - 37 per cent. Iron oxides 10 - 16 per cent. S.G. 2*85 

 to 3-1. The magnesia is less in quantity than the silica, but more 

 than the iron oxides, or the lime, or the alumina, and pyroxene is 

 predominannt over olivine. Not yet known in New Zealand. 

 PEBIDOTITE GROUP. 



Granitic compounds of olivine and iron oxides, usually with 

 enstatite or augite, or both. There is no felspar. Silica 40 - 32 

 per cent. Iron oxides 25 - 30 per cent. S.G. 3-21 to 3-8. The 

 magnesia is equal to or more than the silica, and greater than the 

 iron oxides. Alumina and lime are in small quantity. Magnesia 

 attains its maximum of 30 to 47 per cent. Terrestrial or 

 Meteoric* 



DUNITE. 



A compound of Olivine and Chromite. 

 D%m Mou7ifain, Nelson. — A granular, yellow-green to greyish- 

 green rock with black specks of chromite. S.G. 3-20 to 3-43. 

 Section : Composed of olivine and chromite. The olivine is colour- 

 less, allotriomorphic, from -002 to -10 in diameter, with brilliant 

 polarization colours, and much cracked. The chromite is in grains 

 or in octohedra with rounded edges. Hochstetter, Lectures on 

 the Geology of N-Z., p. 94 ; Zeit. Deut. Geol. Gesell. 1864, xvi., 

 p. 341 - 344 ; Reise der Novara, Geologie von N.Z., pp. 217 - 220; 



I Pallasite Group. It is 85 by (J 

 iron. Crawford, Essay on the ( 





