PLATE X. 



Fig. I. Nephelite Syenite. Crossed Nicols. X 33. The loz- 

 enge-shaped crystal is titanite. The grayish mineral 

 below it is nephelite. Orthoclase appears in the dark 

 and light areas above. 



Fig. 2. Tinguaite. Crossed Nicols. X 33. The ground-mass 

 consists of segirite needles and irregular pieces of 

 feldspar. The porphyritic crystal is orthoclase. 



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