468 R. A. DALY LITCHFIELDITE AND SODA-SYENITES OF MAINE 



properties approximates osannite. In one thin section are grains of a 

 pleochroic, green pyroxene, probably segirite. A little calcite appears to 

 be primary. 



Relation of Litchfieldite to the Nephelite-free Syenites and 

 TO Quartz Pegmatites 



Abont 35 meters northeast of the litchfieldite outcrop at B, at the road, 

 is an exposure of a coarse, pegmatitic syenite which is essentially the 

 equivalent of the mica syenite except for the appearance of secondary 

 muscovite due to crush metamorphism. Probably the two rocks form 

 parts of a single intrusion. A close genetic connection between the two 

 types is more evident in a large boulder occurring about 200 meters west 

 of A. It is chiefly composed of coarse mica syenite bearing only a trace 

 of nephelite, and in the hand specimen practically indistinguishable from 

 the nephelite-free mica syenite in place at C and D. Within the domi- 

 nant syenite of the boulder are narrow schliers of coarse, nephelite-rich 

 litchfieldite. This combination suggests that the litchfieldite is, in part 

 at least, a desilicated, pneumatolytic phase derived from a magma which 

 normally crystallized as a feldspar rock free from nephelite. 



Some of the nephelite-free syenite bears accessory quartz, and in one 

 specimen quartz is pretty clearly of direct magmatic origin and must be 

 rated as an essential constituent. Hence there is some ground for the 

 hypothesis that all these syenites are, in origin, related to the much more 

 abundant, common quartz-microcline pegmatites, which, as sills, lenses, 

 and dikes, cut the crystalline schists of the district. The quartz-bearing 

 pegmatites are strained 'or crushed about as conspicuously as the quartz- 

 free injections. 



Country Rocks 



Throughout the area of figure 1 the intruded rocks form a compara- 

 tively uniform assemblage of rusty- weathering schists and micaceous 

 quartzites, cut by numerous sills of orthogneiss. The schists are gener- 

 ally basic and rich in biotite. Abundant green hornblende, plagioclase, 

 and orthoclase, as well as biotite, were found in one, apparently common, 

 fine-grained phase of the crystalline complex. All transitions between 

 biotite schist and typical quartzite seem to be represented, and one can 

 hardly doubt the sedimentary origin of all these schists. No other sedi- 

 mentary types were found in place, but several angular boulders, evi- 

 dently not far from their parent ledges, were seen to contain thin beds of 



