Mesolite

Mesolith is a commonly occurring mineral from the mineral class of silicates, more specifically, a framework silicate from the group of Faserzeolithe. It crystallizes in the orthorhombic crystal system with the chemical composition Na2Ca2 [ Al6Si9O30 ] · 8H2O and developed primarily long, needle- shaped crystals up hair in radialstrahlig aggregates arranged or firm, porcelain-like masses that are usually colorless or white.

Mineralogical Mesolith is an intermediate link in a continuous chemical mixture series, which is characterized by the exchange of calcium and water instead of sodium. The sodium- rich end member of the series (with the same crystal structure ) is natrolite ( Na2 [ Al2Si3O10 ] · 2H2O), calcium -rich end member scolecite (Ca [ Al2Si3O10 ] · 3H2O ), while Mesolith is of intermediate composition with a significant sodium - and calcium content.

Etymology and history

The name Mesolith was first used in 1813 by the German scholar Adolph Ferdinand Gehlen and Johann Nepomuk Fuchs for a variety of " mesotype ", but without naming the exact locality. The still common definition of the name as an intermediary between natrolite and Skolezit was three years later, in 1816, by JN Fuchs introduced.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Mesolith belonged to the mineral class of " silicates and Germanates " and then to the Department of " framework silicates ( tectosilicates ) " where he along with Gonnardite, Natrolite, Paranatrolith, Skolezit, Thomsonit (Ca ) and Thomsonit - ( Sr), the independent " zeolite group, subgroup Faserzeolithe " was formed.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Mesolith also in the class of " silicates and Germanates " and there in the department of " framework silicates ( tectosilicates ) with zeolitic H 2 O; Family of zeolites " one. This division, however, is further divided according to the structure of the rings, so that the mineral is found in accordance with its construction in the subsection " zeolites with four - ring chains connected via a fifth Si " where there is only together with Gonnardite, Natrolite, Paranatrolith and Skolezit the unnamed group 9.GA.05 forms.

The classification of minerals according to Dana assigns the Mesolith 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, Skolezit, edingtonite, Gonnardite, Cowlesit, Thomsonit - Ca, Sr - Thomsonit and Nabesit in the group " Natrolite and related species " with the system no. Find 77.01.05 within the sub-division of "real zeolites ".

Education and Locations

As the related minerals Skolezit and Natrolite is Mesolith a common decomposition product of basalt and comes together with other zeolites and Apophyllite as hydrothermal formation of drusen in it before. Also, in some igneous and metamorphic rocks occurs Skolezit than divide mineral. Mesolith produced during low-grade metamorphism in the Zeolithfazies.

Known localities include the Faroe Islands, Iceland, Isle of Skye and in India (Maharashtra).

Crystal structure

Mesolith crystallizes in the orthorhombic space group Fdd2 ( Raumgruppen-Nr. 43) with the lattice parameters a = 18.41 Å; b = 56.65 Å and c = 6.55 Å, and eight formula units per unit cell.