Brewsterite
Encyclopedia
Brewsterite is the name of a series of tectosilicate mineral
s of the zeolite
group. Prior to 1997, brewsterite was recognized as a mineral species, but a reclassification in 1997 by the International Mineralogical Association
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 hydrous strontium
and aluminium
silicate
, (Sr,Ba)2Al4Si12O32·10H2O. Small amounts of barium
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, though optical studies have suggested it might be triclinic. 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 isomorphic with heulandite
.
It is named after Sir David Brewster
who described it in 1822. The type locality for the series and for brewsterite-Sr is Strontian
, Argyll
, Scotland
.
It is a hydrothermal mineral occurring in volcanic rocks such as basalt
. Grayish crystals are found at the Giant's Causeway
in County Antrim
. It is found with harmotome
in the lead mines at Strontian
in Argyllshire.
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s of the zeolite
Zeolite
Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that upon rapidly heating the material stilbite, it produced large amounts of steam from water that...
group. Prior to 1997, brewsterite was recognized as a mineral species, but a reclassification in 1997 by the International Mineralogical Association
International Mineralogical Association
The International Mineralogical Association is an international group of 38 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 4000 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 hydrous strontium
Strontium
Strontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
and aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
, (Sr,Ba)2Al4Si12O32·10H2O. Small amounts of barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
is usually present replacing part of the strontium
Strontium
Strontium is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and...
. 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, though optical studies have suggested it might be triclinic. It has one plane of perfect cleavage. The color is white, yellow-white, or gray. The Mohs
Mohs scale of mineral hardness
The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in...
' hardness is 5. It is transparent to translucent. The crystals are prismatic. Brewsterite is isomorphic with heulandite
Heulandite
Heulandite is the name of a series of tecto-silicate minerals of the zeolite group. Prior to 1997, heulandite was recognized as a mineral species, but a reclassification in 1997 by the International Mineralogical Association changed it to a series name, with the mineral species being named:*...
.
It is named after Sir David Brewster
David Brewster
Sir David Brewster KH PRSE FRS FSA FSSA MICE was a Scottish physicist, mathematician, astronomer, inventor, writer and university principal.-Early life:...
who described it in 1822. The type locality for the series and for brewsterite-Sr is Strontian
Strontian
Strontian is the main village in Sunart, an area in western Lochaber, Highland, Scotland, on the A861 road. It lies on the north shore of Loch Sunart, close to the head of the loch...
, Argyll
Argyll
Argyll , archaically Argyle , is a region of western Scotland corresponding with most of the part of ancient Dál Riata that was located on the island of Great Britain, and in a historical context can be used to mean the entire western coast between the Mull of Kintyre and Cape Wrath...
, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
.
It is a hydrothermal mineral occurring in volcanic rocks such as basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
. Grayish crystals are found at the Giant's Causeway
Giant's Causeway
The Giant's Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic eruption. It is located in County Antrim on the northeast coast of Northern Ireland, about three miles northeast of the town of Bushmills...
in County Antrim
County Antrim
County Antrim is one of six counties that form Northern Ireland, situated in the north-east of the island of Ireland. Adjoined to the north-east shore of Lough Neagh, the county covers an area of 2,844 km², with a population of approximately 616,000...
. It is found with harmotome
Harmotome
Harmotome is a mineral, one of the rarer zeolites; a hydrated barium silicate with formula: 5Al5,Si11O32·12. It forms vitreous white well defined monoclinic crystals, often associated with calcite and other zeolites...
in the lead mines at Strontian
Strontian
Strontian is the main village in Sunart, an area in western Lochaber, Highland, Scotland, on the A861 road. It lies on the north shore of Loch Sunart, close to the head of the loch...
in Argyllshire.