Smith. — Alkaline and Nej)heli)ic Bocks, Westland. 131 



Some of the hornblendes are ophitically enclosed in the large 

 cegerines (Plate XIX, fig. 9). 



3. Olivine gabbro-diabase. Large olivines and pink augites 

 are relatively common ; there is a quantity of biotite and brown 

 hornblende in small narrow crystals. The feldspar-labradorite 

 occurs in large plates and in columnar crystals. It is idio- 

 morphic towards both the olivine and the augite, but the latter 

 are allotriomorphic to one another. Some large columnar 

 crystals of labradorite are ophitically enclosed in the olivine. 

 Frequently where the feldspar penetrates an olivine one corner 

 of the feldspar crystal is rounded. The iron-ore, which is plenti- 

 ful and assumes crystallographic forms, is titaniferous. The 

 rock is quite fresh. 



121. Another olivine-augite- feldspar rock, with very sub- 

 ordinate hornblende. It has a typically diabasic groundmass of 

 augite and labradorite, enclosing large grains of olivine without 

 definite shape and phenocrysts of labradorite. One large feld- 

 spar crystal \ in. in length has a narrow margin of clear labra- 

 dorite ; but the interior of the crystal consists of augite and 

 feldspar in about equal proportions, together with a little ilmen- 

 ite. The augite assumes the disposition of a graphic inter- 

 growth ; but, as the whole of it does not extinguish simultaneously, 

 it is evidently an inclusion in the crystal. Grains of ilmenite 

 are plentifully distributed throughout the rock. 



99. Is an augite-feldspar rock, with very subordinate olivine. 

 The phenocrysts are augite in conspicuous plates, with a tendency 

 to idiomorphism and crystals of labradorite-feldspar changing 

 to epidote and calcite. The groundmass consists of feldspar 

 and augite in diabasic relations. The olivine is serpentinised 

 into a clear pale-green mineral, with hardly perceptible dichroism 

 and isotropic. Titaniferous iron-ore is common both as grains, 

 and with rectangular outline, and pyrite occurs in large crystals 

 associated with a pale-green serpentine, which is birefringent 

 in polarised light, shows no definite structure, but is rather a 

 confused aggregate of fibres. 



37. An olivine-augite-feldspar rock, contains the olivines in< 

 large shapeless grains, and has as phenocrysts large augites, 

 perthites, and labradorites with idiomorphic outlines. The 

 groundmass differs from any of the previously described gabbro- 

 diabases in that it consists of a panidiomorphic aggregate of 

 labradorite, partially serpentinised augite, hornblende, and 

 ilmenite. 



130. Another variety is interesting owing to the large develop- 

 ment of the augite phenocrysts, some of which are more than 

 | in. in length. There are inclusions of brown hornblende in 

 the augite crystals. The phenocrysts present good crystal 



