BY W. N. BENSON. 553 



EXPLANATION OF PLATES. 



Plate xxii. 



Geological Map of Newbridge. 



Plate xxiii. 



Fig. L^Andesite from Smith's Hill. At the top a large crystal of augite 



may be clearly seen, and below it a mass of fibrous chlorite. The 



crystals of felspar stand out clearly against a matrix of decomposed 



glassy matter. 

 Fig. 2.— The granophyre referred to on page 532. As may be seen, it is a 



perfect example of an intergrowth of quartz and felspar. 

 Fig.3. — A junction of mica slate and granite. The latter has absorbed a 



little of the colourless part of the slate as may be seen from the fact that 



the biotites project into the granite. This specimen is remarkable for 



the coarseness of grain of the mica slate. 

 Fig. 4. — A junction of mica slate and granophyre. This is very different 



from Fig.3. The slate is finer-grained, and contains much magnetite. 



The granophyre has greatly disrupted the slate. Note the potential 



andalusite crystal on the lower margin. 

 Fig.5. — Chiastolite slate. The chiastolite occurs in black, rectangular 



grains; and is sometimes in a cruciform twin. 

 Fig. 6. — Chiastolite slate. Notice the light halo round each crystal. A 



centimetre scale is shown to give an idea of the size of the crystals. 



