- crystals, are
termed microphenocrysts. Very
large phenocrysts are
termed megaphenocrysts. Some
rocks contain both
microphenocrysts and megaphenocrysts...
-
characteristic of
olivine lamproites is
phlogopite macrocrysts and
microphenocrysts,
together with groundm****
micas that vary in
composition from phlogopite...
-
euhedral phenocrysts of pot****ium feldspar. They are
surrounded by
microphenocrysts and groundm****
composed of hastingsite,
minor hedenbergite and magnetite...
- composition. They
contain pyroxene and
olivine phenocrysts with
subordinate microphenocrysts of
plagioclase and
phlogopite and
inclusions of gray minerals. The...
-
similarities including a
dearth of
pyroxene phenocrysts and
augite microphenocrysts, and both
groups were
probably near-primary melts.
According to Hughes...
- of
sanidine and quartz, sp****
microphenocrysts of
clinopyroxene and orthopyroxene, and
extremely rare
microphenocrysts of fayalite. In the more densely...
- with tubular, open vesicles;
alkali feldspar is in the form of rare
microphenocrysts. It is
compositionally distinct from the
Finlay tephras which may have...
-
These contain phenocrysts of
plagioclase and pyroxene, with
additional microphenocrysts of
ilmenite and magnetite.
Based on the composition, it has been inferred...
- the reds and
browns of the
Laidlaw Volcanics. The rock
consists of
microphenocrysts of
olivine altered to serpentine,
pinkish brown titanaugite, brown...
-
matrix of plagioclase. Augite, biotite,
plagioclase and
hornblende microphenocrysts comprise 1 to 7% of the andesite.
Quartz microxenocrysts are common;...
