-
exception where feldspathoids and quartz-bearing
rocks are
found together is the Red Hill Syenite. Foid, a
contraction of the term
feldspathoid, is applied...
-
gabbro contains up to 10%
feldspathoids rather than quartz. "Foid" in the name is
usually replaced by the
specific feldspathoid that is most
abundant in...
- quartz, feldspars, or
feldspathoids.
classification is
based on the
percentages of quartz,
alkali feldspar, plagioclase, and
feldspathoid out of the total...
- (Q), the
Alkali feldspars (A), the
plagioclase feldspars (P), and the
feldspathoids (F).
Because F and Q
groups cannot simultaneously form in
plutonic rocks—due...
-
substitution by Al3+. As a result,
feldspathoids are
almost never found in ****ociation with quartz. A
common example of a
feldspathoid is
nepheline ((Na, K)AlSiO4);...
- rich in
alkali metals. It is silica-undersaturated and may
contain feldspathoids,
alkali feldspar, phlogopite, and kaersutite.
Augite in
alkali basalts...
- Rock-forming minerals.
Volume 4B.
Framework silicates:
silica minerals.
Feldspathoids and the
zeolites (2nd ed.). London:
Geological Society of London. p...
-
dioritoid in
which quartz makes up less than 5% of the QAPF content,
feldspathoids are not present, and
plagioclase makes up more than 90% of the feldspar...
- Earth's
crust is
predominantly silicate minerals:
mostly feldspars,
feldspathoids, olivine, pyroxenes, amphiboles,
micas and quartz. Rare nonsilicate...
- rock in
which more than 60% (by volume) of light-coloured
minerals are
feldspathoids.
Crystals of
alkali feldspar, plagioclase, biotite, amphibole, pyroxene...
