140 PROCEEDINGS OF THE AMERICAN ACADEMY. 



freely exposed, show a secondary growth of clear microcline substance. 

 These later growths contain abundant inclusions of minute aegirite and 

 riebeckite microliths, sometimes being literally crowded with them. 

 The central part of the crystals appear to be rather freer from inclu- 

 sions than the run of feldspar in the pegmatites. The aegirite occurs 

 crowded in between the feldspars and projects in thickly clustered 

 groups into the free spaces. Its crystals are of all sizes from mere 

 slivers up to crystals 1 cm. broad, 4 cm. thick, and 3, 4 or 10 cm. 

 long. The crystals show a strong tendency toward a composite sub- 

 radial grouping and great irregularities of development. The larger 

 crystals, to even a greater extent than the feldspar, show evidence of 

 a strong solvent action, some of them being largely eaten away or 

 completely honeycombed. Implanted on the surfaces of the feldspar 

 and original aegirite crystallizations are many beautiful, light green 

 patches of very minute, thickly clustered aegirite crystals of later 

 growth. Occasional quartz crystals occur in the pockets or are em- 

 bedded in the feldspar and aegirite near the walls of the main central 

 pocket. 



Implanted on the surfaces of the feldspar and aegirite, particularly 

 in the pockets, are also : many slender, often richly terminated crystals 

 of the rare mineral jyarisite, often including or closely associated 

 with minute crystals of aegirite ; small quartz crystals ; minute, beauti- 

 fully crystallized, black octahedrites, occurring as single crystals, in 

 twinned couplets and in clusters ; ilmenite, in the form of minute flat 

 plates or in rosettes of black or grayish black color. Both the ilmenite 

 and octahedrite are often abundant in the cavities formed by solution 

 in the larger aegirite crystals. On the surfaces of the feldspar and 

 closely associated with the parisite, there is sometimes to be seen a 

 pale pink or buff coating of a material composed of tiny clusters of 

 exceedingly minute, feebly translucent grains. The identity of this 

 coating has not been determined, but it is thought to be zeolitic in 

 character. Some of the aegirite and feldspar is also coated with a thin, 

 blackish-red or brown film of iron and manganese oxides. 



Inside the zonejust described is a remarkable pocket (D in Figure 2) 

 which is unquestionably miarolitic in character. Although a consider- 

 able portion had been removed when the pipe was first examined by the 

 writers, the evidence collected shows that it was almost certainly a 

 single continuous cavity of somewhat irregular contours with a maximum 

 width of about 2 feet, narrowing upward along its strike and broader 

 below than above. Its greatest depth vertically, as observed, was 

 about 3 feet. It was continuous with the central mass of quartz exposed 

 above in the quarry wall. It may be noted here, as indicated by the 



