What is the chemical composition of plagioclase feldspar?
What is the chemical composition of plagioclase feldspar?
| Physical Properties of Plagioclase | |
|---|---|
| Chemical Classification | Silicate |
| Diagnostic Properties | Perfect cleavage, with cleavage faces intersecting at right angles and striations often present on cleavage faces. Well-defined crystals are extremely rare. |
| Chemical Composition | NaAlSi3O8 – CaAl2Si2O8 |
| Crystal System | Triclinic |
What are the end member formulas of the plagioclase feldspar series?
Albite (NaAlSi3O8—usually designated Ab) and anorthite (CaAl2Si2O8—An) are end-members of the plagioclase series.
What is the general formula of feldspar?
| Feldspar | |
|---|---|
| Feldspar crystal (18×21×8.5 cm) from Jequitinhonha valley, Minas Gerais, southeastern Brazil | |
| General | |
| Category | Tectosilicate |
| Formula (repeating unit) | KAlSi 3O 8 – NaAlSi 3O 8 – CaAl 2Si 2O 8 |
What name to be used for a plagioclase with an 75 and AB 25?
Alternate name for the plagioclase series of feldspars. In petrology, the plagioclase series are defined based on their percentage of albite (Ab) to anorthite (An)….About Albite-Anorthite SeriesHide.
| Name | Composition | Formula |
|---|---|---|
| Albite | An10Ab90 to AnAb100 | NaAlSi3O8 |
What is mica chemical formula?
Muscovite
| PubChem CID | 92027383 |
|---|---|
| Chemical Safety | Laboratory Chemical Safety Summary (LCSS) Datasheet |
| Molecular Formula | Al2K2O6Si |
| Synonyms | Muscovite MICA 12001-26-2 Chacaltaite Astrolit More… |
| Molecular Weight | 256.24 |
What is albite and anorthite?
The albite (Ab) – anorthite (An) – ortho- clase (Or) system is one of the most complex systems in which, depending on the water pressure and concentration of components, we can observe different types of phase transi- tions: eutectic (cotectic) and peritectic crystallization with different degrees of solid solution …
What is a solid solution series?
A solid solution series is the compositional range between end-member minerals that share the same basic chemical formula but experience substitution of elements in one or more atomic sites. For example, iron and magnesium can readily replace one another in a mineral.
What is Mica ore?
Mica, any of a group of hydrous potassium, aluminum silicate minerals. It is a type of phyllosilicate, exhibiting a two-dimensional sheet or layer structure. Among the principal rock-forming minerals, micas are found in all three major rock varieties—igneous, sedimentary, and metamorphic.
What are the two components of plagioclase?
We want to observe the behavior of plagioclase under two conditions, one of complete equilibrium during crystallization, and the second of disequilibrium when fractionation occurs and igneous rocks evolve. Two components: high temperature CaAl 2 Si 2 O 8 (anorthite) and low temperature NaAl 2 Si 2 O 8 (albite) plotted along the horizontal axis.
How are the plagioclases different from the feldspars?
Generally, feldspars can be divided into three main groups: Plagioclase feldspars (Na or Ca): NaAlSi 3 O 8 – CaAl 2 Si 2 O 8 (albite and anorthite) Alcalic feldspars (K or Na): K/NaAlSi 3 O 8 (albite and all K-feldspars)
Who was the first person to discover plagioclase?
Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826.
How is plagioclase used as a diagnostic tool?
Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or ‘record-groove’ effect. Plagioclase is a major constituent mineral in the Earth’s crust, and is consequently an important diagnostic tool in petrology for identifying the composition, origin and evolution of igneous rocks.