Portal logo
124
PEGMATITES AND ASSOCIATED ROCKS OF MAINE.
GRAPHIC GRANITE.
Much of the quartz and feldspar of certain pegmatite deposits is regularly intergrown in the form of graphic granite. (See PI. XVIII and p. 22.) At the majority of feldspar quarries most of the material shipped is graphic granite, though whatever pure feldspar occurs is usually also included and serves to raise the percentage of feldspar in the whole mass. Analyses of four specimens of graphic granite are given below. These analyses were made by George Steiger in the laboratory of the United States Geological Survey.