Albite is a

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more pro ...

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) felds ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

. It is the sodium

endmember An endmember (also end-member or end member) in mineralogy is a mineral that is at the extreme end of a mineral series in terms of purity of its chemical composition. Minerals often can be described as solid solutions with varying compositions of ...

of the plagioclase

solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The wor ...

series. It represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula . It is a

tectosilicate Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...

. Its color is usually pure white, hence its name from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

, . It is a common constituent in felsic rocks.

Properties

Albite crystallizes with

triclinic 180px, Triclinic (a ≠ b ≠ c and α ≠ β ≠ γ ) In crystallography, the triclinic (or anorthic) crystal system is one of the 7 crystal systems. A crystal system is described by three basis vectors. In the triclinic system, the crystal i ...

pinacoidal forms. Its

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...

is about 2.62 and it has a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by t ...

of 6–6.5. Albite almost always exhibits

crystal twinning Crystal twinning occurs when two or more adjacent crystals of the same mineral are oriented so that they share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals that are tightly ...

often as minute parallel striations on the crystal face. Albite often occurs as fine parallel segregations alternating with pink

microcline Microcline (KAlSi3O8) is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slo ...

perthite Perthite is used to describe an intergrowth of two feldspars: a host grain of potassium-rich alkali feldspar (near K-feldspar, KAlSi3O8, in composition) includes exsolved lamellae or irregular intergrowths of sodic alkali feldspar (near albite, N ...

as a result of exolution on cooling. There are two variants of albite, which are referred to as 'low albite' and 'high albite'; the latter is also known as 'analbite'. Although both variants are triclinic, they differ in the volume of their unit cell, which is slightly larger for the 'high' form. The 'high' form can be produced from the 'low' form by heating above High albite can be found in meteor impact craters such as in

Winslow Winslow may refer to: Places United Kingdom * Winslow, Buckinghamshire, England, a market town and civil parish * Winslow Rural District, Buckinghamshire, a rural district from 1894 to 1974 United States and Canada * Rural Municipality of Winslo ...

, Coconino Co., Arizona, United States. Upon further heating to more than the

crystal symmetry In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns t ...

changes from triclinic to

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

; this variant is also known as 'monalbite'. Albite melts at . Oftentimes, potassium can replace the sodium characteristic in albite at amounts of up to 10%. When this is exceeded the mineral is then considered to be

anorthoclase The mineral anorthoclase ((Na,K)AlSi3O8) 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 KAlSi3O8 and ...

Occurrence

It occurs in

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

and pegmatite masses (often as the variety cleavelandite), in some

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenat ...

deposits, and forms part of the typical

greenschist Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically and 2–10 kilobars (). Greenschists commonly have an abundance of green minerals such as chlorite ...

metamorphic facies for rocks of originally

basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...

ic composition. Minerals that albite is often considered associated with in occurrence include biotite, hornblende, orthoclase, muscovite and quartz.

Discovery

Albite was first reported in 1815 for an occurrence in Finnbo,

Falun Falun () is a city and the seat of Falun Municipality in Dalarna County, Sweden, with 37,291 inhabitants in 2010. It is also the capital of Dalarna County. Falun forms, together with Borlänge, a metropolitan area with just over 100,000 inhabitan ...

Dalarna Dalarna () is a '' landskap'' (historical province) in central Sweden. English exonyms for it are Dalecarlia () and the Dales. Dalarna adjoins Härjedalen, Hälsingland, Gästrikland, Västmanland and Värmland. It is also bordered by Norwa ...

, Sweden.

Use

Albite is used as a gemstone, albeit semi-precious. Albite is also used by geologists as it is identified as an important rock forming mineral. There is some industrial use for the mineral such as the manufacture of

glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling ( quenching ...

and ceramics.

References

External links

Mineral galleries
{{Authority control Tectosilicates Feldspar Triclinic minerals Luminescent minerals Gemstones Minerals in space group 2