-
Perthite or
perthitic texture is used to
describe an
intergrowth of two feldspars: a host
grain of pot****ium-rich
alkali feldspar (near K-feldspar, KAlSi3O8...
-
Major minerals include plagioclase, microcline, quartz, and muscovite.
Perthitic textures on the
microcline are possible.
Minor minerals include biotite...
- be on a
scale from
microscopic to
readily observable in hand-sample;
perthitic texture forms when Na-rich
feldspar exsolve in a K-rich host. The opposite...
-
feldspar compositions during cooling of an
intermediate composition. The
perthitic textures in the
alkali feldspars of many
granites can be seen with the...
- with
distinctive phenocrysts of blue
quartz (a rare
quartz color) and
perthitic feldspar (light grayish-orangeish). The brown, fine-grained groundm****...
- volcanics,
which they
intrude into. They are
granite with
granophyric quartz,
perthitic pot****ium feldspar,
biotite and magnetite. They are
intrusive into the...
-
feldspar in
granites is
typically orthoclase or
microcline and is
often perthitic. The
plagioclase is
typically sodium-rich oligoclase.
Phenocrysts are...
- 35% of the
feldspar content. Such
feldspars often are
interleaved as
perthitic components of the rock. When
ferromagnesian minerals are
present in syenite...
-
Syenite all
contain primarily alkali feldspar, with many
rocks displaying perthitic igneous texture. The
perthites range from
microperthite (lamellae barely...
- microcline, and few
feldspar phenocrysts. The main
minerals are quartz,
perthitic orthoclase, and plagioclase. The dark
mineral is
mostly biotite. Also...
