Feldspar, any of a group of aluminosilicate minerals that contain calcium, sodium, or potassium. Feldspard make up more than half of Earth crust, and professional literature about them constitutes a large percentage of the literature of mineralogy.
Of the more than 3,000 known mineral species, less than 0.1 percent make up the bulk of Earth crust and mantle. These and an additional score of minerals serve as the basis for naming most of the rocks exposed on Earth surface.
Description and Identifying Characteristics Feldsparis derived from the German word feld,which means field, and spar, which means crystal. This name reflects the minerals abundance, as most crystalline material found in the field is feldspar. Potassium feldspard are the feldspar minerals in which the silicate tetrahedral and aluminum tetrahedra are bound with potassium ions, rather than sodium or calcium ions as in the plagioclase feldspar subgroup. The potassium feldspar group is composed of three mineral polymorphs, each having the same chemical composition, but slightly different crystal structures.
Technically these are distinct minerals, but their physical properties are so similar that they are usually only identified as potassium feldspar in the field. Using other minerals in the rock to determine the host rocks identity is often the most useful guide to their probable identity. felsic plutonic igneous rocks and metamorphic rocks Microcline
Feldspar, any of a group of aluminosilicate minerals that contain calcium, sodium, or potassium. Feldspard make up more than half of Earth's crust, and professional literature about them constitutes a large percentage of the literature of mineralogy.
Of the more than 3,000 known mineral species, less than 0.1 percent make up the bulk of Earth's crust and mantle. These and an additional score of minerals serve as the basis for naming most of the rocks exposed on Earth's surface.
Description and Identifying Characteristics Feldspar is derived from the German word feld,which means field, and spar, which means crystal. This name reflects the minerals abundance, as most crystalline material found in the field is feldspar. Potassium feldspard are the feldspar minerals in which the silicate tetrahedral and aluminum tetrahedra are bound with potassium ions, rather than sodium or calcium ions as in the plagioclase feldspar subgroup. The potassium feldspar group is composed of three mineral polymorphs, each having the same chemical composition, but slightly different crystal structures.
Technically these are distinct minerals, but their physical properties are so similar that they are usually only identified as potassium feldspar in the field. Using other minerals in the rock to determine the host rocks identity is often the most useful guide to their probable identity. felsic plutonic igneous rocks and metamorphic rocks Microcline
Gypsum is an evaporite mineral most commonly found in layered sedimentary deposits in association with halite, anhydrite, sulfur, calcite, and dolomite. Gypsum (CaSO4.2H2O) is very similar to Anhydrite (CaSO4). The chemical difference is that gypsum contains two waters and anhydrite is without water. Gypsum is the most common sulfate mineral
Uses of Gypsum
Gypsum uses include: manufacture of wallboard, cement, plaster of Paris, soil conditioning, a hardening retarder in Portland cement. Varieties of gypsum known as satin spar and alabaster are used for a variety of ornamental purposes; however, their low hardness limits their durability.
Gypsum is an evaporate mineral most commonly found in layered sedimentary deposits in association with halite, anhydrite, sulfur, calcite, and dolomite. Gypsum (CaSO4.2H2O) is very similar to Anhydrite (CaSO4). The chemical difference is that gypsum contains two waters and anhydrite is without water. Gypsum is the most common sulfate mineral.
kaolin, also called china clay, soft white clay that is an essential ingredient in the manufacture of china and porcelain and is widely used in the making of paper, rubber, paint, and many other products. Kaolin is named after the hill in China (Kao-ling) from which it was mined for centuries. Samples of kaolin were first sent to Europe by a French Jesuit missionary around 1700 as examples of the materials used by the Chinese in the manufacture of porcelain.
In its natural state kaolin is a white, soft powder consisting principally of the mineral kaolinite, which, under the electron microscope, is seen to consist of roughly hexagonal, platy crystals ranging in size from about 0.1 micrometre to 10 micrometres or even larger.
These crystals may take vermicular and booklike forms, and occasionally macroscopic forms approaching millimetre size are found. Kaolin as found in nature usually contains varying amounts of other minerals such as muscovite, quartz, feldspar, and anatase.
In addition, crude kaolin is frequently stained yellow by iron hydroxide pigments. It is often necessary to bleach the clay chemically to remove the iron pigment and to wash it with water to remove the other minerals in order to prepare kaolin for commercial use.
Nepheline is an important feldspathoid mineral. It is white, grey or yellow in colour with a vitreous lustre and a poor cleavage. The name Nepheline comes from the Greek word nephele, which means cloud, because it becomes strongly clouded when put in strong acid.
Nepheline only forms in silica-poor rocks. It is almost never associated with quartz. It may be found in some contact metamorphosed rocks otherwise it occurs in alkaline complexes in igneous rocks. Nepheline is mostly found in the rock Nepheline Syenite in nature.
