-
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...
- (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...
- quartz, feldspars, or
feldspathoids.
classification is
based on the
percentages of quartz,
alkali feldspar, plagioclase, and
feldspathoid out of the total...
-
component of
lapis lazuli is
lazurite (25% to 40%),[citation needed] a blue
feldspathoid silicate mineral of the
sodalite family, with the
formula Na7Ca(Al6Si6O24)(SO4)(S3)...
- Rock-forming minerals.
Volume 4B.
Framework silicates:
silica minerals.
Feldspathoids and the
zeolites (2nd ed.). London:
Geological Society of London. p...
- rich in
alkali metals. It is silica-undersaturated and may
contain feldspathoids,
alkali feldspar, phlogopite, and kaersutite.
Augite in
alkali basalts...
- rock in
which more than 60% (by volume) of light-coloured
minerals are
feldspathoids.
Crystals of
alkali feldspar, plagioclase, biotite, amphibole, pyroxene...
-
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);...
- rock with
aphanitic to
porphyritic texture. It is
composed mostly of
feldspathoids, pyroxenes, olivine, and
calcic plagioclase and
forms from
magma low...
