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PROCEEDINGS OF THE AMERICAN ACADEMY. 



Figure 2. 



Cross-section through the lower portion of the large Fallon quarry pipe at 

 a point where the central pocket has its maximum development. The ver- 

 tical dimension is about 10 ft., the horizontal about 6 ft. 



A, dark marginal zone, similar in character to that described for Figure 1, 

 but as a whole somewhat less sharply defined, and, in its lower portions, 

 merging almost imperceptibly into the granite without. 



B, main zone of the pipe showing a more or less well defined outer band 

 of graphic-granite with streaks and patches of the same in other parts, but 

 in the main consisting of an inequi-granular but prevailingly coarse mixture 

 of microcline-albite microperthite, quartz, large, scattered aegirite-riebeckite 

 crystals, aegirite, zircon, etc. Occasional quartz blebs and small crystal 

 pockets are also present. 



C, zone consisting of a porous, inequi-granular mixture of microcline and 

 aegirite. This becomes exceedingly open in texture as the walls of the central 

 pocket are approached and exhibits beautifully free crystallizations of aegirite 

 and microcline on which are implanted crystals of parisite, octahedrite, and 

 ilmenite. 



D, microlitic cavity more or less completely filled with quartz crystals, free 

 and attached, fluorite octahedra, fragments of all portions of the surrounding 

 pegmatite, except the dark margin, and the whole embedded in a closely 

 felted mass of beautifully fibrous, grayish-blue crocidolite. 



