Brewsterite is the name of a series of

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, the crystalline forms of silica (silicon dio ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

s of the

zeolite Zeolites are a group of several microporous, crystalline aluminosilicate minerals commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a meta ...

group. Prior to 1997, brewsterite was recognized as a mineral species, but a reclassification in 1997 by the

International Mineralogical Association Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. ...

changed it to a series name, with the mineral species being named brewsterite-Sr and brewsterite-Ba. Brewsterite-Sr, the more common of these, is a hydrous

strontium Strontium is a chemical element; it has symbol Sr and atomic number 38. An alkaline earth metal, it is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is exposed to ...

and

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

, . Small amounts of

barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...

is usually present replacing part of the strontium. The appropriate species name depends on the dominant element. The species are visually indistinguishable, and the series name brewsterite is still used whenever testing has not been performed. It is generally considered to be

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...

, though optical studies have suggested it might be

triclinic class=skin-invert-image, 180px, Triclinic (a ≠ b ≠ c ≠ a and α, β, γ, 90° pairwise different) In crystallography, the triclinic (or anorthic) crystal system is one of the seven crystal systems. A crystal system is described by three b ...

. It has one plane of perfect cleavage. The color is white, yellow-white, or gray. The Mohs' hardness is 5. It is transparent to translucent. The crystals are prismatic. Brewsterite is isomorphous with heulandite. It is named after Sir

David Brewster Sir David Brewster Knight of the Royal Guelphic Order, KH President of the Royal Society of Edinburgh, PRSE Fellow of the Royal Society of London, FRS Fellow of the Society of Antiquaries of Scotland, FSA Scot Fellow of the Scottish Society of ...

(1781–1868) who described it in 1822. The type locality for the series and for brewsterite-Sr is

Strontian Strontian (; ) is the main village in Sunart, an area in western Lochaber, Scottish Highlands, Highland, Scotland, on the A861 road. Prior to 1975 it was part of Argyllshire. It lies on the north shore of Loch Sunart, close to the head of th ...

Argyll Argyll (; archaically Argyle; , ), sometimes called Argyllshire, is a Shires of Scotland, historic county and registration county of western Scotland. The county ceased to be used for local government purposes in 1975 and most of the area ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

. It is a hydrothermal mineral occurring in volcanic rocks such as

basalt Basalt (; ) is an aphanite, 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 planetary surface, surface of a terrestrial ...

. Grayish crystals are found at the

Giant's Causeway The Giant's Causeway () is an area of approximately 40,000 interlocking basalt columns, the result of an ancient volcano, volcanic fissure eruption, part of the North Atlantic Igneous Province active in the region during the Paleogene period. ...

County Antrim County Antrim (named after the town of Antrim, County Antrim, Antrim, ) is one of the six counties of Northern Ireland, located within the historic Provinces of Ireland, province of Ulster. Adjoined to the north-east shore of Lough Neagh, the c ...

. It is found with harmotome in the lead mines at

Argyllshire Argyll (; archaically Argyle; , ), sometimes called Argyllshire, is a historic county and registration county of western Scotland. The county ceased to be used for local government purposes in 1975 and most of the area now forms part of ...

References

IMA Zeolite Classification
* Zeolites of the World, Rudy W. Tschernich, 1992

External links

structure type BRE
Zeolites Monoclinic minerals Minerals in space group 11 {{silicate-mineral-stub