Ussingite

Ussingite is a rarely occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the triclinic crystal system with the chemical composition of Na2 [ OH | AlSi3O8 ], so it is a sodium -aluminum silicate with additional hydroxide. Structurally, it belongs to the layer silicates.

Ussingite is transparent to translucent and develops rarely tabular or pseudo-cubic crystals. He usually can be found in the form of fine -grained to coarse mineral aggregates of white, pink, light violet to blue-violet or reddish violet color with white stroke color.

Special Features

Ussingite is soluble in HCl.

Etymology and history

Ussingite was first discovered and described in the Ilímaussaq intrusion in Kangerdluarssuq Fjord near Narsaq in southwestern Greenland in 1915 by Ove Bøggild Balthasar ( 1872-1956 ). He named the mineral after Niels Viggo Ussing (1864-1911), a Swedish professor of mineralogy and member of the Royal Danish Academy of Sciences.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the ussingite belonged to the department of " framework silicates ( tectosilicates ), with zeolites ", where he led the unnamed group formed as a single member VIII/J.14.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the ussingite other hand, in the department of " layer silicates ( phyllosilicates ) " a. This is further divided according to the structure of the layers, so that the mineral is found in accordance with its construction in the subsection "transitional structures between phyllosilicates and other silicates ", where it forms the unnamed group 9.EH.20 the only member.

The mainly common in English-speaking classification of minerals according to Dana assigns the ussingite in the class of " silicates " and there in the department of " framework silicates: Al- Si lattice " field. Here he is the only member of the unnamed group 76.03.03 within the subdivision: to find " tectosilicates Al- Si lattice with other Be / Al / Si gratings ".

Education and Locations

At its type locality, the Ilímaussaq intrusion in Greenland, located ussingite formed as a secondary mineral in the local pegmatites and sodalite syenite with aegirine, microcline and natrolite. In geologically similar find area Lovozero Tundra on the Russian Kola Peninsula could be detected as more paragenesis albite yet. In addition, the mineral was found on Kola still Kukiswumtschorr, on Yukspor and Vuonnemiok River Valley in the Chibinen.

At Mont Saint- Hilaire is ussingite found in sodalite xenoliths in intruded, alkaline gabbro - syenites along with eudialyte, Griceit, Lovozerit, Lueshit, Natrophosphat and Villiaumit.

Crystal structure

Ussingite crystallizes in the triclinic space group P1 ( Raumgruppen-Nr. 2) with the lattice parameters a = 7.256 Å; b = 7.686 Å; c = 8.683 Å; α = 90.75 °; β = 99.75 ° and γ = 122.48 ° and two formula units per unit cell.