Plagioclase ((Ca,Na)AlSi 3 O 8) is one of the forms of feldspar. It is an aluminum-containing silicate. This feldspar is distinguished from the orthoclase form by its content of calcium and sodium. The feldspars are the most abundant minerals on the earth. In the Bowen reaction series, plagioclase can be seen to form throughout the process of magma crystallization in what is called the continuous reaction series.
http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/feldspar.html
Beneficial properties of feldspars include good dispersability, high chemical inertness, stable pH, high resistance to abrasion, low viscosity at high filler loading, interesting refractive index and resistance to frosting. The products used in such applications are generally fine-milled grades.
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Feldspar is what's called a rock-forming mineral, very common and usually making up a large part of the rock. In sum, any glassy mineral that's slightly softer than quartz is very likely to be a feldspar. The main mineral that might be confused with feldspar is quartz. Besides hardness, the biggest difference is how the two minerals break. Quartz breaks in curvy and irregular shapes (conchoidal fracture).
http://geology.about.com/od/minerals/a/aboutfeldspar.htm
Feldspars are a group of closely related minerals that together are the most abundant mineral in the Earth's crust. A thorough knowledge of the feldspars is what separates geologists from the rest of us.
http://geology.about.com/od/minerals/a/aboutfeldspar.htm
Plagioclase Orthoclase. Feldspar is a name given to a class of aluminum-containing silicates which are sometimes called light silicates or nonferromagnesian silicates since they don't contain iron or magnesium. The feldspars include orthoclase (KAlSi 3 O 8) and plagioclase ((Ca,Na)AlSi 3 O 8).
http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/feldspar.html
Feldspar is by far the most abundant group of minerals in the earth's crust, forming about 60% of terrestrial rocks. Most deposits offer sodium feldspar as well as potassium feldspar and mixed feldspars. Feldspars are primarily used in industrial applications for their alumina and alkali content.
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Feldspar. Feldspar is the mineral name given to a group of minerals distinguished by the presence of aluminum (Al) and the silica ion (SiO4) in their chemistry. This group includes aluminum silicates of soda (sodium oxide), potassium (potassium oxide), or lime (calcium oxide). Feldspar is the single most abundant mineral group on Earth. Together, the varieties of feldspar account for one half of the Earth's crust. The minerals included in this group are orthoclase, microcline, and the plagioclase feldspars. They form in a variety of thermal environments, during the crystallization of liquid rock (magma), by metamorphism of rocks deep in the earth, and in sedimentary processes.
http://scienceviews.com/geology/feldspar.html
This feldspar is distinguished from the plagioclase form by its content of potassium. The feldspars are the most abundant minerals on the earth. Polycrystalline orthoclase is usually light cream to salmon pink in color, although color is not a reliable indicator of mineral type.
http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/feldspar.html
How to Tell Feldspar. Feldspars are hard minerals, all of them with a hardness of 6 on the Mohs scale. This lies between the hardness of a steel knife (5.5) and the hardness of quartz (7).
http://geology.about.com/od/minerals/a/aboutfeldspar.htm
The mineralogical composition of most feldspars can be expressed in terms of the ternary system Orthoclase (KAlSi3O8), Albite (NaAlSi3O8) and Anorthite (CaAl2Si2O8). Chemically, the feldspars are silicates of aluminium, containing sodium, potassium, iron, calcium, or barium or combinations of these elements.
http://www.ima-na.org/?page=what_is_feldspar
the most abundant mineral group on earth is feldspars. these minerals contain
The most abundant mineral group on earth is feldspars that contains calcium and sodium. This feldspar is distinguished from the orthoclase form by its content of calcium and sodium.