B. K. Emerson—Dyke of Elaolite-syenite in New Jersey. 305 
While the calcites are limpid, the orthoclase crystals, opaque 
white by reflected light, are of deep reddish brown by trans- 
mitted light, and this color, which is caused by the abundance 
of a very fine red dust, is spread uniformly over every portion 
of every crystal, except in one slide where they are quite fresh, 
and enclose in considerable number small perfect spheres of a 
deep brown to black color, which seem to be some hydrocarbon 
compound which has been included in the forming crystal in a 
liquid state. This black carbonaceous matter is scattered here 
and there through the mass, and it is sometimes aggregated in 
the midst of a brownish substance in such a manner as to sug- 
gest an incipient stage in the formation of chiastolite crystals. 
All the rest of the micaceous ground-mass is mottled by a 
lens everywhere incomplete crystalline outlines. 
_ The component next in importance is eegirite, which appears 
in black elongated crystals up to 8™™ in length, upon which I 
was able to measure the angle of the prism 92° 47’. The min- 
eral fuses with somewhat greater difficulty than the Norwegian 
egirite, and tinges the flame yellow. The surface of many of 
the crystals is brightly iridescent, as is sometimes the case 
s 
with the arfvedsonite from Kangerdluarsuk, and the crystals 
