Trans. N.Z. Inst., Vol. LII. 



Plate XXIX. 



Fig 1. 



Fig. 



Fig. I. 



Fig. 



-Granodiorite. The lower half of the photomicrograph illustrates a large crystal 

 of amphibole ophitically enclosing plagioclase. Above this, granulation and 

 shadow extinction are just detectable in the quartz. Crossed nicols. Magni- 

 fication, 20 diameters. 



-Banded dioritic gneiss. The granulitic structure is well exhibited. Crossed 

 nicols. Magnification, 21 diameters. 



liG. 3. 



Fig. 4. 



Fig. 3. — Dolerite showing the lath-like foi-m of the feldspars, which are ophitically 

 enwrapped by amphibole. Crossed nicols. Magnification, 21 diameters. 



Fig. 4. — Trachyte. The upper portion of the coarse white mineral is plagioclase, the 

 lower sanidine, the intervening dark area being a gap in the section. Crossed 

 nicols. Magnification, 21 diameters. 



Face p. i2/.l 



