Is anorthoclase a feldspar?
Anorthoclase is the only alkali feldspar that is not K-feldspar. It is sodic in composition, optically triclinic and characterized by a twinning similar to microcline but on a smaller scale.
Where is anorthoclase found?
Anorthoclase occurs in high temperature sodium rich volcanic and hypabyssal (shallow intrusive) rocks. The mineral is typically found as a constituent of the fine grained matrix or as small phenocrysts which may occur as loose crystals in a weathered rock.
How do you identify anorthoclase?
Upon macroscopic examination, anorthoclase is also generally identified merely as an alkali feldspar except by those who are acquainted with the rocks known to contain anorthoclase. The rock-forming plagioclases can seldom be identified as to species by macroscopic means.
How do you classify feldspar?
In the classification of igneous rocks of the International Union of Geological Sciences (IUGS), the feldspars are treated as two groups: the alkali feldspars and the plagioclase feldspars. The alkali feldspars include orthoclase, microcline, sanidine, anorthoclase, and the two-phase intermixtures called perthite.
What is Perthitic texture?
Strictly speaking a perthite has blebs or irregular lamellae of sodic feldspar within potassic alkali feldspar, however, the term perthite is often used to describe all types of exsolution in the feldspars.
What is feldspar worth?
Feldspar Market worth 745.7 Million USD 2022.
What is CaAl2Si2O8?
Calcium aluminosilicate (CaAl2Si2O8)
What is anorthoclase?
Anorthoclase is strictly a K-rich variety of albite. It was long used (and still is by petrologists) as an intermediate member of the high albite – sanidine ( alkali feldspar) solid solution series, in which the albite member exists in larger proportion.
Is orthoclase a feldspar?
The sense of Haüy’s naming of Orthoclase was that the mineral was a Feldspar, but he did not specify a type locality or a chemical analysis. Orthoclase is a component of many rocks, especially alkalic and plutonic acid rocks, also granites, pegmatites and syenites.
Is anorthoclase a high albite?
Anorthoclase is an intermediate member of the high albite – sanidine alkali feldspar solid solution series. Intermediate members of this series, high albite, anorthoclase and high sodium sanidine are stable at temperatures of 600 °C (1,112 °F) and above.
What is the IMA symbol for anorthoclase?
The mineral anorthoclase ( (Na,K)AlSi 3 O 8) is a crystalline solid solution in the alkali feldspar series, in which the sodium-aluminium silicate member exists in larger proportion. It typically consists of between 10 and 36 percent of KAlSi 3 O 8 and between 64 and 90 percent of NaAlSi 3 O 8.. It’s IMA symbol is Ano .