Trans. N.Z. Inst., Vol. XXXIV. 



Pi.. XXVI. 



E. 

 Mount Eden Basalt. 



Magnified 50 Diameters. 



Ground-mass vitreous, consisting of small triclinic needle- 

 shaped feldspar crystals and microliths, minute augite 

 crystals and specks of magnetite imbedded in a glassy 

 magma. 



Olivine crystals. 



Augite crystals 



Feldspar crystals 



Magnetite specks 



The olivine is abundant; the smaller crystals can only be 

 recognised under crossed nicols. 



ROCK SECTIONS.— Mulgan. 



