-
common members of the
feldspar group are the
plagioclase (sodium-calcium)
feldspars and the
alkali (pot****ium-sodium)
feldspars.
Feldspars make up
about 60%...
-
poured out vast
floods of
black basalt,
containing feldspar, augite, olivine, and iron ores in a
black gl****y base. They are
highly liquid when discharged,...
-
Oligoclase is a rock-forming
mineral belonging to the
plagioclase feldspars. In
chemical composition and in its
crystallographic and
physical characters...
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spreading outwards through a fine
grained or
gl****y rock. In
variolites there are
straight or
feathery feldspar crystals (usually oligoclase)
forming pale-colored...
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anorthoclase (a type of
feldspar)
found in the
immediate area
surrounding Mount Erebus near
McMurdo Station, Antarctica. This type of
feldspar is rich in sodium...
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describing igneous rocks that are
relatively rich in
elements that form
feldspar and quartz. It is
contrasted with
mafic rocks,
which are
richer in magnesium...
-
alkali oxides must be
present as
aegirine or
sodic amphibole rather than
feldspar. The
chemistry of
volcanic rocks is
dependent on two things: the initial...
- əlaɪt/ RY-ə-lyte) is the most silica-rich of
volcanic rocks. It is
generally gl****y or fine-grained (aphanitic) in texture, but may be porphyritic, containing...
- are
usually phenocrysts of
feldspar,
mostly orthoclase,
though a
varying amount of
plagioclase is
often present. The
feldspars are
usually full and cloudy...
-
collected from
Earth and the Moon.
Close examination of this
sample shows gl****y feldspar,
which can be
shown to have
formed under unique conditions, common...
