Campsetit.—On Crystalline Rocks. 453 
“One of the arguments against the igneous origin of granite is that its 
quartz has a s.g. of 2-6, identical with that of silica, derived from aqueous 
solution, while the s.g. of fused silica is only 2-2” (Rutley’s “ Petrology,” 
207 
p. 207). 
Professor Haughton, in his annual address to the Geological Society of 
Dublin in 1862, in alluding to a table of the specific gravities of natural and 
artificially fused rocks, remarks :—‘‘It appears to me that the column of 
differences greatly strengthens the arguments of those chemists and geolo- 
gists who believed that water played a much more important part in the 
formation of granites and trap rocks than it has done in the production of 
trachytes, basalts, and lavas, and that they owe their relatively high s.g. to 
its agency.” 
The accompanying table from Dr. Page’s “« Geology” shows admirably 
the component parts of granite, the felspar occurring in two varieties, 
“ orthoclase ” and “ oligoclase,” the former being associated with white 
and black mica (uniaxial and biaxial). 
A table of felspars is also shown for the sake of reference. It shows the 
¢rystallographic relations with the chemical. 
Grani Potash ~ 
‘In Granite, Gneiss, Syenite' 
and True Volcanic Rocks 
