Sentence Examples with the word Felsitic

The latter are represented by large contemporaneous deposits of tuff and felsitic lava which in the Snowdon District are several thousand feet thick.

These are penetrated by intrusions of granitic and felsitic character; one of these masses in Papa Stour is a handsome pink felsite.

Often this felsitic devitrified glass is so fine-grained that its constituents cannot be directly determined even with the aid of the microscope, but chemical analysis leaves little doubt as to the real nature cf the minerals which have been formed.