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.