What is the luster of schist?
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. These larger crystals reflect light so that schist often has a high lustre, i.e. it is shiny. …
What are the physical properties of sillimanite?
Sillimanite
| Physical Properties | |
|---|---|
| Habit | Acicular Long, slender prisms Fibrous Subparallel aggregates and splays Fine-grained fibrous mats |
| Color | White to brown |
| Hardness | 6 to 7 |
| Specific gravity | 3.23 |
Is mica schist shiny?
It is often referred to as schistosity because of its large mica flakes. Large crystals cause schist rocks to reflect lots of light which gives it a very shiny appearance. The large crystals in schist indicate the amount of pressure and temperature that was used to make the rock.
Why is mica schist shiny?
The shiny surfaces that these schists often show are due to the presence of the flaky mineral, mica, formed during the metamorphism.
What kind of rocks are made of sillimanite?
It occurs with andalusite, kyanite, potassium feldspar, almandine, cordierite, biotite and quartz in schist, gneiss, hornfels and also rarely in pegmatites. Natural sillimanite rocks cut into the required shape and size are used mainly in glass industries.
How is sillimanite used on a large scale?
Natural sillimanite rocks cut into the required shape and size are used mainly in glass industries. Sillimanite is the best raw material for the manufacture of high alumina refractories or 55-60% alumina bricks. But its use on large scale is not possible due to its fine grading and high cost.
Where is sillimanite found in the United States?
Sillimanite has been found in Brandywine Springs, New Castle County, Delaware. It was named by the State Legislature in 1977 as the state mineral of Delaware by the suggestion of the Delaware Mineralogical Society. ^ “WebMineral entry”. Retrieved 2009-12-19. ^ MacKenzie, W. S.; Guilford, C. (1980). Atlas of rock-forming minerals in thin section.
What kind of rock is a schist made of?
Schist is a medium-grained strongly-foliated crystalline metamorphic rock, formed by dynamic metamorphism, that can be readily split into thin flakes or slabs due to the well-developed parallelism of more than 50% of the minerals present, particularly those of lamellar or elongate prismatic habit, e.g., mica and amphiboles.
