Leucitite

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Leucitite sample from Vesuvius (Italy)

Leucitite is a volcanic rock ( vulcanite ). It belongs to the foidites , and consists largely of leucite (K [AlSi 2 O 6 ]), various clinopyroxenes and dark olivines ((Mg, Fe) 2 [SiO 4 ]). Nepheline and / or representatives of the sodalite group Sodalite , Haüyn and Nosean can also occur as further, felsic mixture parts, but these are less important than leucite. If the proportion of leucite (or of the totality of foid minerals) in the felsic constituents falls below 90%, the term tephritic or phonolithic leucitite is used, with less than 60% the designation after the foid mineral is given up (cf. the classification in the route iron diagram ).

Leucitite is an example of a silicon dioxide - under saturated volcanic rock (see silicon saturation ). It arises in a volcanic melt that is undersaturated with silica and enriched in potassium .

properties

Leucitite is gray to dark gray, depending on the proportion of broken crystals. It has an often porphyry structure with well-developed, bright crystals in the form of icositetrahedra (formerly also called leucitoeder ) of leucite and dark orthorhombic crystals of olivine, which are embedded in a fine-grained matrix. Particularly in sub-volcanic form , leucitite can also be evenly fine-grained, the leucite crystals sometimes have less sharp edges with decreasing size.

In terms of construction, leucitite is used for floors and stairs.

Occurrence

Since it is a volcanic rock, the deposits are also classified close to the volcano, which are often attributable to anorogenic intraplate volcanism . In Germany, for example, leucitite can be found in the Eifel near Mayen and Hillesheim , rarely in the Vogelsberg , in the rest of Europe in the Italian landscape of Tuszien near the city of Vallerano and in the Czech Republic in the area around Valeč v Čechách . The central Italian volcanic area with Vesuvius is also an important occurrence in Europe .

Web links

Commons : Leucitite  - collection of images, videos and audio files
  • Leucitite. In: mindat.org. Hudson Institute of Mineralogy, accessed June 29, 2019 .

Individual evidence

  1. ↑ a b Mineral Atlas: Leucitite (Wiki)
  2. ↑ a b Roland Vinx: Rock determination in the field . 3. Edition. Spectrum, Heidelberg 2011, ISBN 978-3-8274-2748-9 , p. 246-247 .
  3. ↑ Website about natural stone
  4. ^ Wilhelm Meyer: Geology of the Eifel . 3. Edition. Schweizerbart, Stuttgart 1994, ISBN 3-510-65161-8 , p. 351 .
  5. ↑ William Schottler: Notes on the Geological Map of the Grand Duchy of Hesse, Leaf Laubach . 1st edition. Hessischer Staatsverlag, Darmstadt 1918, p. 41-42 .