Listvenite is a medium and low temperature metasomatic rock consisting of carbonates (most often ankerite ), quartz and muscovite or fuchsite (chromic mica ) mixed with various minerals ( talc , chlorite , actinolite , albite , tourmaline , rutile , sphene ).
Listvenites have a bright green (from fuchsite) or gray (with colorless muscovite) color. Often due to the decomposition of carbonates, iron hydroxides appear, which give brown shades to the larch.
Listvenite is formed as a result of the larchization process [1] (hydrothermal processing) of serpentinite and other ultrabasic and basic rocks.
The textures are slate, massive, sometimes cavernous. The structures are heteroblast, fine and medium grained.
Chemical composition (% of mass): SiO 2 - 35; Mg - 10-20; CaO - 15-30; СО 2 - 20-40; FeO + Fe 2 O 3 - 10-20. The density of 2.8-3.1 g / cm 3 [2] .
Typically, larchites occur in the form of lenses and vein-like bodies among schistose and weakly carbonated rocks.
First discovered in the Middle Urals ( Berezovskoye field ) and described by German geologist Gustav Rosa [3] in 1842. A characteristic form of manifestation is near-crack belt changes with a thickness of up to 1.5 m.
Deposits and ore occurrences of gold , mercury , cobalt , and copper are associated with larchites.
Application
Listvenite is of value mainly as a decorative-facing material. green foliage from the Ural deposits became most famous. According to Academician Fersman, larchwood refers to the ornamental stones of class III. Larch trees of beautiful bright green colors with various shades are used as an ornamental stone for facing buildings and for the production of art products. The development of this material as ornamental raw material was carried out by the domestic stone-cutting industry in the second half of the 20th century [4] .
Notes
- ↑ Listvenitization is the process of changing ultrabasic (mainly serpentinite) and basic rocks under the influence of hydrothermal solutions, as a result of which larchites are formed.
- ↑ Small Mountain Encyclopedia . In 3 t. = Mala gіrnicha encyclopedia / (In Ukrainian). Ed. V.S. Beletsky . - Donetsk: Donbass, 2004. - ISBN 966-7804-14-3 .
- ↑ Listvenite // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- ↑ Decorative varieties of colored stone of the USSR, Moscow, "Nedra", 1989, p. 111
Links
- Listvenite on the “Minerals Catalog” Photos, description, deposits
- Larch on Geovikipedia
- Listvenites in the Geological Dictionary .