[ 72 ] 



EXPLANATION OF PLATES II., III., and IV. 



Plate II. 



Figure 1. — Veins of Felspar traversing Beryl. Section through a crystal 

 of altered Beryl, parallel to axis of hexagonal prism. 

 Light polarized, (x 18 diameters.) 



Figure 2. — Broken down Beryl. Section ri*ear base of mixed Beryl and 

 Orthoclase. Light polarized, fx 18 diameters.) 



N.B. — As the letters have been omitted, the edges 

 referred to may be identified thus : — lowest left-hand 

 edge (about one centimetre in length) is the edge d ; 

 the adjoining edges c ; the uppermost edge broken by 

 the fissure is b, and the next adjoining edge is a. 



Plate III. 



Figure 3. — Iolite in situ, showing markings of Orthoclase. Section in 

 altered Beryl. 



Figure 4. — Group of Iolite crystals removed from cavities in mixed 

 Beryl and Orthoclase. Light polarized, (x 18 dia- 

 meters.) 



N.B. — The description of these two last figures has 

 been transposed on the Plate. 



Plate IV. 

 Figure 5. — Badiating Beryl in granite matrix. 



