PLATE XLVII. 



FIG. 1. 

 GLAUCOPHANE-EPIDOTE-SCHIST. 



ANGLESEA MONUMENT. 



Magnified 80 diameters. Polarizer only ; short axis right and left. 



The minerals represented are glaucophane (30), epidote (28), quartz (24), 

 and iron-ores. 



The individual crystals of glaucophane are elongated in the direction of 

 their vertical axes, and they are so arranged in the rock that their longest axes 

 are, in most cases, approximately parallel to each other. The figure represents 

 the slide as it appears when viewed with rays vibrating parallel to the direction 

 in which the longest axes (corresponding to the axes of least elasticity) of most of 

 the individuals lie. The dominant colour of the glaucophane is that characteristic 

 of rays vibrating parallel to 7. One individual (30a) cuts the schistosity obliquely 

 and gives indications of the violet tint characteristic of rays vibrating parallel 

 to p. 



The epidote occurs for the most part in grains, which, however, frequently 

 show a tendency to elongation in the direction of the orthodiagonal. 



In other portions of the same slide quartz is more abundant than in the 

 part represented in the figure. It occurs in granular aggregates which are 

 penetrated by idiomorphic glaucophane. 



In addition to the minerals mentioned above the rock contains a white mica 

 and minute vividly polarizing grains of a biaxial mineral possessing a very high 

 refractive index (sphene). 



FIG. 2. 



GLAUCOPHANE. 



Magnified 200 diameters. Polarizer only ; short axis right and left. 



This figure represents cross-sections of glaucophane from the same rock. 

 A and d l represent the same individual. As the and ft axes lie approximately 

 in the plane of the cross-section, this figure represents the colours characteristic 

 of rays vibrating parallel to these axes. Combining this figure with Fig. 1, we 

 have the complete scheme of pleochroism : a, pale yellow ; ft, violet ; 7, blue. 

 The cross-sections are bounded by the prismatic faces (110) with indications 

 of the clino-pinacoid (010). 



FIG. 3. 



SPHENE. 



Magnified 50 diameters. Ordinary light. 



This figure represents sections of sphene occuring in the mica-diorite of 

 Pen Voose (see Fig. 1, Plate XXXII.). The colourless inclusions in 31a are 

 composed of felspar. 31b represents a kernel of iron ore zoned by sphene. 



FIG. 4. 



NOSE AN. 



Magnified 60 diameters. Ordinai^y light. 



This figure represents a very thin section of the phonolite of the Wolf rock 

 (see Fig. 1, Plate XLL). The distribution and arrangement of inclusions in the 

 nosean may be clearly recognized. The ground-mass is formed of segirine and 

 nepheline. The small nepheline crystals show indications of crystalline outline. 



FIG. 5. 



MICROPEGMATITE. 



Magnified 50 diameters. Nicols crossed. 



This represents the micropegmatite which plays the role of ground-mass in 

 the quartz-gabbro (augite-diorite) of Carrock Fell. 



