Laumontite
- Lomonit
- Laumonit
- Leonhardite
Laumontite is a commonly occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the monoclinic crystal system with the composition Ca [ Al2Si4O12 ] · 4H2O is therefore seen chemically a hydrous calcium silicate. Occasionally, a portion of the aluminum may be replaced by beryllium (Be). Structurally laumontite is one of the tectosilicates and there to the group of zeolites.
Laumontite most developed prismatic to columnar crystals with a square cross section, but can also be found in the form radialstrahliger, fibrous and massive mineral aggregates. In pure and unweathered form it is colorless and transparent. But it can also appear white and gray, pink, yellowish or brownish accept by foreign admixtures to golden brown color by multiple refraction due to polycrystalline training and by the loss of crystal water (dehydration ), the transparency decreases accordingly.
Special Features
Laumontite are already in a dry environment with the time part of its water of crystallization, and should therefore be stored in airtight containers. Dehydrated Laumonit is brittle and can even disintegrate under low mechanical stress.
Etymology and history
Was first discovered in 1785 by Laumontite the French mineralogist Gillet de Laumont ( 1747-1834 ) in a lead mine near the French community Huelgoat (Brittany ). Described and named the mineral 1803 by Abraham Gottlob Werner after its discoverer, but first in the spelling Lomonit to play the French pronunciation onomatopoeic. 1805 took over Robert Jameson Werner's description and name in his work System of Mineralogy.
By René -Just Haiiy the spelling of the mineral name was changed again in 1809 Laumonit, until finally in 1821 is still valid today notation Laumontite coined Karl Caesar von Leonhard.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the laumontite belonged to the department of " framework silicates ( tectosilicates ), with zeolites ", where he along with boggsite, dachiardite - Ca, dachiardite -Na, Direnzoit, edingtonite, ferrierite K, Mg, ferrierite, ferrierite Na Gottardiit, mordenite, and Mutinait Terranovait the subset of " Faserzeolithe II " with the system number. VIII/J.22 formed within the zeolite group.
The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification places the laumontite also in the department of " framework silicates ( tectosilicates ) with zeolitic H 2 O; Family of zeolites " one. However, this is further subdivided according to the crystal structure, so that the mineral is found in accordance with its construction in the subsection " chains of simply connected four -rings ", where it forms the unnamed group 9.GB.10 the only member.
The mainly common in English-speaking classification of minerals according to Dana assigns the laumontite in the class of " silicates and Germanates " and there in the department of " framework silicates: Zeolite - group " field. Here he is with analcime, Hsianghualith, pollucite and Wairakite in the group " analcime and related species " with the system no. 77.01.01 found within the subdivision "Real zeolites ".
Modifications and varieties
As leonhardite an opaque by partial loss of water and white tarnished variety of laumontite is named. It was named in 1843 by Johann Reinhard Blum in honor of Karl Caesar von Leonhard ( 1779-1862 ).
Education and Locations
Like other zeolites, also Laumonit in crevices of basalt, andesite, granite or metamorphic rocks different forms. In addition, laumontite is also formed in hydrothermal calcareous deposits. Accompanying minerals other zeolites, but also Apophyllite and chlorite, calcite, Datolith, heulandite and / or stilbite may occur.
As a frequent mineral formation laumontite has already been demonstrated in many localities, where so far (as of 2013) are considered to be known around 1000 localities. Apart from its type locality Huelgoat the mineral in France still has to date held at Cambo- les- Bains, Aquitaine, at Espira -de- l'Agly (municipality Rivesaltes ) in Languedoc- Roussillon, in Arnave, Salau (Ariège ), port d'Agrès and in the Aure valley in Midi-Pyrenees and at Saint -Michel -de- Chaillol in Provence -Alpes- Côte d' Azur to light.
Known due to exceptional Laumontitfunde among others, the mines in the Pandulena Hills is in India, where colorless and white, needle-shaped crystals of up to 38 centimeters long came to light. Also from India, specifically from Pune and Mumbai knows you pseudomorphs of prehnite after laumontite. After all, up to 15 centimeters long crystals were recovered in the " Pine Creek Mine " at Mount Morgan in Inyo County ( California).
In Germany they found laumontite among others in the Clara mine in Baden- Württemberg, in several places in the Bavarian Forest ( Hauzenberg, Forest churches ) in Bornberg / Herbornseelbach and high cities ( Bensheim ) in Hesse, near Bad Harzburg and Saint Andreas mountain in Lower Saxony, the Clemens Berg in North Rhine -Westphalia, in Baumholder, on Potschberg and Lower churches ( West Palatinate ) in Rhineland -Palatinate, at the Petersberg near Halle in Saxony -Anhalt, in the mining operation " Willi Agatz " in Saxony and Thuringia in Weitisberga.
In Austria laumontite has been found in many places in the Hohe Tauern and the Kor in Carinthia, on Mitter Bachgraben in the community Dunkelsteinerwald and at several locations in the Waldviertel in Lower Austria, in the Gastein Valley and Habachtal in Salzburg and at some points in Styria, Tyrol and Upper Austria.
In Switzerland, the mineral previously occurred mainly in the cantons of Graubünden ( Albignagletscher, Sedrun ), Ticino (Valle Maggia ), Uri and Wallis ( Binn Valley, Goms )
Other localities lie among others in Algeria, Antarctic, Argentina, Australia, Azerbaijan, Belgium, Brazil, Bulgaria, Chile, China, Costa Rica, Denmark, Ecuador, in the Fiji Islands, Iceland, Indonesia, Iran, Italy, Japan, Canada, Kyrgyzstan, Cuba, Madagascar, Mexico, Namibia, New Zealand, Nicaragua, Norway, the Philippines, Poland, Puerto Rico, Réunion, Romania, Russia, Sweden, Slovakia, Spain, South Africa, Taiwan, Tanzania, Thailand, Czech Republic, Turkey, Ukraine, Hungary, the United Kingdom ( UK) and the United States of America (USA).
Crystal structure
Laumonit crystallizes in the monoclinic space group C2 / m ( Raumgruppen-Nr. 12) with the lattice parameters a = 14.72 Å; b = 13.07 Å; c = 7.56 Å and 112.0 ° and β = 4 formula units per unit cell.
The crystal structure consists of a Laumontite the [ AlO 4 ] - and [ SiO4 ] tetrahedra framework with four -, six -and ten -membered rings which form channels and cages in parallel.