-
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,...
-
rapidly solidifies.
Hence such
rocks are fine-grained (aphanitic) or even
gl****y.
Basalt is the most
common extrusive igneous rock and
forms lava flows,...
-
Oligoclase is a rock-forming
mineral belonging to the
plagioclase feldspars. In
chemical composition and in its
crystallographic and
physical characters...
-
spreading outwards through a fine
grained or
gl****y rock. In
variolites there are
straight or
feathery feldspar crystals (usually oligoclase)
forming pale-colored...
-
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...
-
white or greyish-white and opaque,
though meionite is
found as
colorless gl****y crystals in the
ejected limestone blocks of
Monte Somma, Vesuvius. The hardness...
-
grains of
silicate minerals (usually
quartz or
feldspar),
consisting of very
narrow planes of
gl****y material arranged in
parallel sets that have distinct...
-
plagioclase feldspar solid solution series. In
pyroclastic rocks in
which alkalis predominate over Ca, K-
feldspar such as
sanidine or
albite Na-
feldspar are found...
- 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...
