What minerals are found in mica schist?
Main minerals: quartz, mica (muscovite, chlorite, biotite), feldspar, talc, graphite, hornblende, garnet.
Where is garnet mica schist formed?
This garnet mica schist comes from the Proterozoic Moine metasediments of Glenshiel, Inverness-shire, Scotland and were metamorphosed during the Caledonian orogeny. In thin section the main fabric is defined by muscovite and biotite micas. Quartz and plagioclase are also present, with minor opaque minerals.
How is garnet schist formed?
Schist is medium grade metamorphic rock, formed by the metamorphosis of mudstone / shale, or some types of igneous rock, to a higher degree than slate, i.e. it has been subjected to higher temperatures and pressures.
How is garnet formed?
Most garnet forms when a sedimentary rock with high aluminium content, such as shale, is metamorphosed (subjected to heat and pressure). The high heat and pressure breaks the chemical bonds in the rocks and cause minerals to recrystallise.
How is garnet mica schist formed?
Schist is a foliated metamorphic rock made up of plate-shaped mineral grains that are large enough to see with an unaided eye. To become schist, a shale must be metamorphosed in steps through slate and then through phyllite. If the schist is metamorphosed further, it might become a granular rock known as gneiss.
How does Garnet form in schist?
The black, gray, and white grains are mostly silt or smaller size grains of quartz and feldspar. The garnet has grown by replacing, displacing, and including the mineral grains of the surrounding rock.
How does garnet mica schist form?
Where do the mica minerals come from as slate metamorphoses into schist?
Where do the mica minerals come from as slate metamorphoses into schist? The mica minerals grow from the clay minerals in the slate as it metamorphoses. If a rock melts, can it be considered metamorphic? No because metamorphic rocks don’t melt.
What type of metamorphic rock is garnet?
The rock-forming garnets are most common in metamorphic rocks. A few occur in igneous rocks, especially granites and granitic pegmatites….Origin and occurrence.
| Common occurrences of rock-forming garnets | |
|---|---|
| spessartine | granitic pegmatites; silica-rich skarns; metamorphosed manganese-bearing rocks |
What is garnets chemical composition?
Garnet is a rather complex mineral that has a general chemical formula of R3R2(SiO4)3, where R3 is a bivalent (gives up two electrons) metal and R2 is a trivalent (gives up three electrons) metal when forming a chemical bond.
What type of Garnet is found in schist?
The most common garnet is probably almandine which is found in abundance as porphyroblasts in schist, in pegmatites, and very occasionally in gabbros and mafic metavolcanic rocks. Almandine in schist is typically associated with muscovite, biotite, quartz, staurolite, kyanite, sillimanite, plagioclase feldspar, chlorite, and others.
What is mica schist used for?
Talc schist is used in ceramic glazes. Mica schist can be used to make vermiculite , a common component of potting soil. Greenish schist slabs — perhaps chlorite schist — were found by archeologists to have been used for roofing in the Bronze Age .
What gems are found with garnet schist?
Gem-quality garnet, kyanite, tanzanite, emerald, andalusite, sphene, sapphire, ruby, scapolite, iolite, chrysoberyl and many other gem materials are found in schist. Gem materials found in schist are often highly included.
What colors are in the mica schist rock?
Aug 21, 2014 – Mica schist metamorphic rocks are gray to silver in color and typically shiny due to the mica present. Schist is a metamorphosed clayey rock and is fine-grained.