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Plagioclase (/ˈplædʒ(i)əˌkleɪs, ˈpleɪdʒ-, -ˌkleɪz/ PLAJ-(ee)-ə-klayss, PLAYJ-, -klayz) is a
series of
tectosilicate (framework silicate)
minerals within...
- pot****ium, or barium. The most
common members of the
feldspar group are the
plagioclase (sodium-calcium)
feldspars and the
alkali (pot****ium-sodium) feldspars...
- and
plagioclase makes up more than 65% of the
total feldspar content.
Gabbroids are
distinguished from
dioritoids by an
anorthite (calcium
plagioclase) fraction...
-
sodic plagioclase (An70–85),
norites (
plagioclase-orthopyroxene), and
gabbronorites (
plagioclase-clinopyroxene-orthopyroxene) with
similar plagioclase compositions...
-
effect (schiller).
Labradorite is an
intermediate to
calcic member of the
plagioclase series. It has an
anorthite percentage (%An) of
between 50 and 70. The...
-
intrusive igneous rock
composed mostly of quartz,
alkali feldspar, and
plagioclase. It
forms from
magma with a high
content of
silica and
alkali metal oxides...
-
quartz in
plagioclase. The
intergrowths are
microscopic in scale,
typically with
maximum dimensions less than 1 millimeter. The
plagioclase is sodium-rich...
-
contains amphibole,
especially hornblende and actinolite, as well as
plagioclase feldspar, but with
little or no quartz. It is
typically dark-colored...
- phaneritic,
intrusive igneous rock
characterized by its composition:
mostly plagioclase feldspar (90–100%), with a
minimal mafic component (0–10%). Pyroxene...
- (lamellae) of
different alkali feldspars (orthoclase and sodium-rich
plagioclase).
Polished moonstones often display chatoyancy ("cat's eye" effect),...
