Edingtonite

• Antiëdrit
• Tetraedingtonit

Edingtonite -1Q: tetragonal

Edingtonite -1Q: tetragonal- scalenohedral 42m

Edingtonite is a rarely occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the orthorhombic crystal system with the composition Ba [ Al2Si3O10 ] · 4H2O, is so chemically seen a hydrated barium aluminum silicate framework and a member of the zeolite group.

Edingtonite usually develops pseudotetragonale crystals with prismatic, pyramidal or disphenoidem habit, but also granular to massive aggregates of translucent white, gray or pink to reddish color with white stroke color. However, in thin layers, it can also be colorless and perfectly transparent.

Special Features

Edingtonite is pyroelectric and piezoelectric, ie builds on interval -like change in temperature or deformation an electrical voltage.

Before the blowpipe the mineral can be difficult to melt to a colorless glass.

Etymology and history

The mineral was named after the Scottish mineral collector James Edington ( 1787-1844 ).

Was first described by Wilhelm Ritter von Haidinger edingtonite, who discovered the mineral in the cavities of the mineral Thomsonit from the collection of James Edington. The Thomsonit itself came from the Kilpatrick Hills ( Kilpatrickhügel ) near Glasgow in the formerly independent, Scottish county of Dunbartonshire.

The term Antiëdrit in 1832 elected by Johann Friedrich August Breithaupt for a tetragonal crystallizing, antihemiëdrisch pyramidal edingtonite.

Classification

The 9th edition used since 2001, valid and of the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the edingtonite also in the class of " silicates and Germanates " there, however, in the already fine divided department of the " framework silicates ( tectosilicates ) with zeolitic H 2 O; Family of zeolites " one. This department is also further divided according to the type of framework structure, so that the mineral is found in accordance with its construction in the subdivision of " zeolites associated with four -ring chains via a fifth Si " where there is only together with Kalborsit the unnamed group 9.GA.15 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the edingtonite in the class of " silicates and Germanates " and there in the department of " framework silicates: Zeolite - group " field. Here he is with Natrolite, Tetranatrolith, Paranatrolith, Mesolith, Skolezit, Gonnardite, Cowlesit, Thomsonit - Ca, Sr - Thomsonit and Nabesit in the group to find " Natrolite and related species " 77.01.05 within the sub-division of "real zeolites ".

Education and Locations

Edingtonite formed by hydrothermal processes in cavities and fissures of mafic volcanic rocks, nepheline syenite - carbonatite or where it is to be found among others in paragenesis with analcime, brewsterite, calcite, Harmotome, Natrolite, Prehnite and Thomsonit.

A rare mineral formation edingtonite has so far (as of 2011) are detected only at a few localities, of which approximately 20 are considered to be known. Apart from its type locality Kilpatrick Hills the mineral still occurred in the quarries of Loanhead ( Ayrshire ) and Guisachan ( Highlands ) in Scotland. More Locations in the UK are Disgwylfa Hill in the English Shropshire and Welsh Wethel in Radnorshire.

Known for its rich finds well-formed crystals in aggregates of several centimeters in size is mainly the Ice River alkaline complex of the Golden Mining Division in the Province of British Columbia. In addition, the mineral is found in Canada but also in the " Brunswick No. 12 Mine " in New Brunswick and in Poudrett quarry at Mont Saint- Hilaire in Quebec.

Furthermore, it was edingtonite among other things still in the " Jacupiranga Mine" at Cajati in the Brazilian state of São Paulo, at Staré Ransko near Havlíčkův Brod in the Czech region of Moravia, in the " Shiromaru Mine" in the district Nishitama -gun on the Japanese island of Honshu, in several places in the Chibinen on the Russian Kola Peninsula, in Bölet ( Bölets Ängar ) near Undenäs in Sweden and at Big Creek and Ash Creek in the State of California.

Crystal structure

Edingtonite comes in two modifications of different crystal structure, referred to as edingtonite -1O and edingtonite -1Q.

• Edingtonite -1O crystallizes in the orthorhombic space group 212121 ( Raumgruppen-Nr. 18) with the lattice parameters a = 9.55 Å; b = 9.67 Å; c = 6.52 Å and two formula units per unit cell.

• Edingtonite -1Q ( Tetraedingtonit ) crystallizes tetragonal in the space group P421m ( Raumgruppen-Nr. 113) with the lattice parameters a = 9.58 Å and c = 6.53 Å and two formula units per unit cell.