Are garnets in schist?
Schist is often the host rock for a variety of gemstones that form in metamorphic rocks. 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.
How is schist with garnet 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.
What is a garnet mica schist?
Garnet mica schist is a variation of mica schist, a metamorphic rock formed by medium grade metamorphism which is usually a combination of both heat and pressure applied to the original rock, often a clay, mud or shale.
What is garnet mica schist made of?
Garnet-Mica Schist
| Type | Metamorphic Rock |
|---|---|
| Composition | Muscovite, Biotite, Garnet, Quartz, Feldspar |
| Index Minerals | Garnet |
| Color | Shiny, medium gray |
| Miscellaneous | Small-sized dark red-brown garnets on foliation surfaces |
What is muscovite schist?
Mica schist, the most common schistose rock and the second most common metamorphic rock, is composed mostly of mica (usually biotite or muscovite) and smaller amounts of quartz.
What minerals are in muscovite schist?
Main minerals: quartz, mica (muscovite, chlorite, biotite), feldspar, talc, graphite, hornblende, garnet.
How is chlorite schist formed?
Chlorite minerals most often form in rock environments where minerals are altered by heat, pressure, and chemical activity. Metamorphic rocks rich in chlorite might include phyllite and chlorite schist. Another environment of chlorite mineral formation is in oceanic crust descending into subduction zones.
Is garnet schist valuable?
However, some varieties have an attractive appearance which makes them useful as a facing or decorative stone. Schist may be worth mining if it contains useful minerals in large concentration. Common minerals extracted from schistose metamorphic rocks are garnet, kyanite, talc and graphite.
Where is garnet mica schist found?
The garnet-muscovite schist shown above is early Late Cretaceous in age (89 to 92 million years). It comes from Garnet Ledge, southeastern Alaska, USA. Rocks from this locality contain near-gem-quality almandine garnets. Chlorite schist (8.2 cm across) with black, octahedral crystals of magnetite (Fe3O4).
Where is garnet schist found?
There are various features that distinguish schist rocks made from sedimentary rocks or those made from igneous. It can be found in many countries including Brazil, parts of the US and Ireland.
Are schist rocks worth anything?
Where is chlorite commonly found?
igneous rocks
Chlorite is commonly found in igneous rocks as an alteration product of mafic minerals such as pyroxene, amphibole, and biotite.