PLATE XXV. 



FIGS. 1 and 2. 

 OUVINE-GABBRO. 



LOCH CORUISK, SKVK. 



Magnified 25 diameters. Fig. 1, Ordinary light ; Fig. 2, under crossed nicols. 



The minerals represented are plagioclase (10), diallage (7) and olivine (1). 



These figures represent the granitic structure in its typical development. 

 The rocks are of Tertiary age. They have been described by Professor JUDD 

 (Q.J.G.S., Vol. XLIL, 1886, p. 50). 



la is a cross-section of a pyroxene showing the prismatic cleavages and also 

 a separation parallel to the one of the vertical pinacoids. 



~Sote. The section is thicker than those generally employed so that the 

 felspars polarize in brilliant colours instead of neutral tints. 



