Lazurite

• Azurite
• English: Lazurite ( cyanus )

Lazurite is a rare occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes predominantly in the cubic crystal system with the chemical composition of (Na, Ca) 8 [S2 | ( AlSiO4 ) 6]. Known, though rarely, however, orthorhombic or triclinic Lasurite (see crystal structure).

Lazurite is especially found as a component of lapis lazuli, but also occurs in pure form dodecahedral and rare cubic crystals or granular to massive and ingrown mineral aggregates.

Etymology and history

Lasurit was in the lapis lazuli deposit Ladjuar Medam near Sar -e -Sang District Kuran va Munjan ( Badakhshan province ) discovered in Afghanistan and in 1890 first described scientifically by Waldemar Christofer Brøgger and H. Bäckström. They named the mineral based on its color after the Persian word لاژورد / lāžward for blue or " sky blue ".

The Georgian Prince Vaxushti Batonishvili ( Wakuschti Batonischwili, 1696-1757 ) described in his historical chronicle Life Kartlis an existing since the Early Bronze Age mining area in the southeast of Georgia south of the city Bolnisi, equating iron, copper and Lasurit were processed at the time.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Lasurit belonged to the mineral class of " silicates and Germanates " and there to the general ward of the " framework silicates ( tectosilicates ) " where he along with Bicchulith, Haüyn, Kamaishilith, nosean, sodalite, tsaregorodtsevite and tugtupite the independent " sodalite " with the system no. VIII/J.11 formed.

The 9th edition used since 2001, valid and of the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Lasurit also in the class of " silicates and Germanates " there, however, in the already fine divided department of the " framework silicates ( tectosilicates ) without zeolitic H2O " one. This department is also further divided according to the possible presence of other anions in the formula so that the mineral is found according to its composition in the subsection " framework silicates ( tectosilicates ) with additional anions ," where it along with Bicchulith, Danalith, Genthelvin, Haüyn, Helvin, Kamaishilith, nosean, sodalite, tsaregorodtsevite and tugtupite the " sodalite Danalith group " with the system no. 9.FB.10 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the Lasurit in the class of " silicates and Germanates " there, however, in the department of " framework silicates: Al- Si lattice " field. He is also a member of the " sodalite " with the system no. 76.02.03 within the subdivision " framework silicates: Al- Si lattice, feldspar and related species " to find.

Education and Locations

Lazurite is formed by contact metamorphism in limestone, where it is associated in addition to calcite, among others, still with diopside, forsterite, Haüyn, Humit, muscovite and pyrite to find.

A rare mineral formation Lasurit has so far (as of 2011) only to be detected less than 50 localities. Apart from its type locality Ladjuar Medam the mineral still occurred in Afghanistan in other places in the province of Badakhshan and Panjshir province.

Other localities lie among others in Chile, Canada, Italy, Myanmar, Russia, Sweden, Slovakia, Tajikistan, and in various states of the United States of America.

Crystal structure

Lazurite occurs in three modifications of different crystal structure, the cubic modification Lasurit -1C is the most common form of training and in the space group P43n ( Raumgruppen-Nr. 218 ) with the lattice parameters a = 9.10 Å, and one formula unit per unit cell crystallized.

The other two polymorphs are:

• Lasurit - 6O: Orthorhombic, space group Pnna ( Raumgruppen-Nr. 52) with the lattice parameters a = 9.07 Å; b = 12.83 Å and c = 38.49 Å and 6 formula units per unit cell.

• Lasurit -4A: Triklin in the space group P1 ( Raumgruppen-Nr. 1) with the lattice parameters a = 9.07 Å; b = 12.90 Å; c = 25.71 Å; α = 90.0 °; β = 90.1 ° and γ = 90.2 °, and four formula units per unit cell.