-
Biotite is a
common group of
phyllosilicate minerals within the mica group, with the
approximate chemical formula K(Mg,Fe)3AlSi3O10(F,OH)2. It is primarily...
- not as
useful for
rocks in
other facies with
higher Ca-garnets and
mixed biotites.
Several calibrations have been
completed that take into
account the non-ideal...
-
somewhat equigranular matrix of
feldspar and
quartz with
scattered darker biotite mica and
amphibole (often hornblende)
peppering the
lighter color minerals...
-
minor amounts of
muscovite mica as the
lighter colored mineral components.
Biotite and
amphiboles often in the form of
hornblende are more
abundant in granodiorite...
- also be
named after a
characteristic component such as
garnet gneiss,
biotite gneiss,
albite gneiss, and so forth.
Orthogneiss designates a
gneiss derived...
- only one
cleavage plane. Talc has
basal cleavage. Mica (like
muscovite or
biotite) also has
basal cleavage; this is why mica can be
peeled into thin sheets...
-
known as
magnesium mica.
Phlogopite is the
magnesium endmember of the
biotite solid solution series, with the
chemical formula KMg3AlSi3O10(F,OH)2. Iron...
- effect.
Vermiculite forms by the
weathering or
hydrothermal alteration of
biotite or phlogopite.
Large commercial vermiculite mines exist in the
United States...
- hornblende/actinolite +/-
albite +/-
biotite +/-
quartz +/-
garnet (calcite +/- wollastonite) Pelite; quartz,
orthoclase +/- albite, +/-
biotite +/-
actinolite +/- garnet...
-
igneous rocks which have
primary mineralogy consisting of
amphibole or
biotite, and with
feldspar in the groundm****.
Lamprophyres are not
amenable to...