- The
feldspathoids are a
group of
tectosilicate minerals which resemble feldspars but have a
different structure and much
lower silica content. They occur...
-
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...
- The
acronym QAPF
stands for "Quartz,
Alkali feldspar, Plagioclase,
Feldspathoid (Foid)",
which are the four
mineral groups used for
classification in...
-
Ancient Gr**** νεφέλη (nephélē) 'cloud'), is a rock-forming
mineral in the
feldspathoid group – a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that...
- at
least 10% of the
mineral content consists of quartz, feldspar, or
feldspathoid minerals,
classification begins with the QAPF diagram. The
relative abundances...
-
essential alkali feldspar.
Relatively minor plagioclase and
quartz or a
feldspathoid such as
nepheline may also be present. This is
reflected in the position...
-
formula Na6Ca2[(CO3)2|Al6Si6O24]·2H2O. It is
classed as a
member of the
feldspathoid group of minerals; the
alkali feldspars that are poor in silica. Yellow...
- quartz, feldspars, or
feldspathoids.
classification is
based on the
percentages of quartz,
alkali feldspar, plagioclase, and
feldspathoid out of the total...
- content. The
relative amounts of quartz,
alkali feldspar, plagioclase, and
feldspathoid is
particularly important in
classifying intrusive igneous rocks. Intrusions...
-
olivine Es****ite –
Igneous rock type Foidolite –
Igneous rock rich in
feldspathoid minerals Gabbro – Co****-grained
mafic intrusive rock Granite – Type...
