It consists chiefly of felspar laths (labradorite) with 

 prismatic or granular titaniferous augite, finely crys- 

 tallised magnetite and small phenocrysts of olivine. These 

 last are passing into colourless highly doubly refracting 

 talc. Flow structure is not well developed as a rule, though 

 some slight trachytic arrangement is noticeable among 

 the felspar. Chlorite replaces augite in the more weathered 

 specimens and a little dusty carbonate may be present. 

 The analysis shows that the rock is more closely related 

 to the nepheline basalts than to the normal basalts, but I 

 have not been able to determine the presence of nepheline 

 in its almost isotropic base, nor was it noted by Mr. Card. 



(A) Dundas basalt analysed by H. P. White 1 



(B) Average basalt (161 basalts, 17 olivine diabases, 11 

 melaphyres, and 9 dolerites). 2 



(0) Average nepheline basalt (16 specimens. 



K„0 1-78 152 



H 2 0- -88i , R0 



H,0+ 3 17 I lb - 



C0 3 -60 — 



OrthoeUse 



1056 





23-58 





-;>;:; 



Nepheline 



5-11 





•70 



Diopside 



9-21 



MnO 

 NiCoO 

 BaO 



1 (A) Eec. Gta L Bur? H.S.W ., we. at. mpra 



2 (B and C) quoted from R. A. Daly, Average Chemical t.'omposit 



; , ,, .. !•; \-. A ->..l. -f Arts and Soiemv*. \ >>\. 

 No. 7, Jan. 1910. Averages No. 40 and 69. 



