slide is rotated in a vertical plane, moving always slowly toward the
top of the cavity and thus indicating that the vacuole is of lower
density than the inclosing fluid. An examination of a number of thin
sections of Maine granites shows that the inclusions in the quartzes of
both pegmatites and granite are similar jn character and distribution
and are not noticeably different in abundance. In both types of rocks
the fluidal cavities are generally arranged in bands, most of which are
nearly straight, though some are wavy. Some of these bands terminate
abruptly at the border of a quartz grain, but others pass without
change or deflection from one quartz grain to another.
In
the rose quartz illustrated in Plate VI some of the bands of fluid
inclusions in the larger quartz grains terminate abruptly at the
sheared and re-crystallized zone and others continue into it. Bands of
inclusions also pass from grain to grain within the sheared zone. It
appears therefore that some of the bands of inclusions are not only
later than the original crystallization of the quartz but are later
even than the straining, granulation, and recrystallization which
subsequently affected it. The tint and degree of opacity exhibited by
the quartz seems to be dependent in some measure on the abundance and
distribution of the inclusions. In several pieces of dirty-gray, opaque
quartz, iuclusions were particularly abundant and were not confined to
bands but were also scattered irregularly through the quartz. A thin
section of transparent smoky quartz from the Berry quarry in Poland
was seen under the highest available power of the microscope (540
diameters) to be clouded with inclusions so minute that their
character could not be made out. They were not arranged ill bands and
the usual type of fluidal cavities was entirely absent. It is not
uncommon for the inclusions in pegmatite quartzes to be in two dominant
sets of bands nearly at right angles to each other and
