Moldavite (Czech: VltavÃÆ'n ) is a green forest, green olive or turquoise stone of vitreous silica projectile formed by impacted meteorites in southern Germany (NÃÆ'¶rdlinger Ries Crater) that occurred about 15 million years ago. This is a kind of tektite.
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Studi awal
Moldavite was introduced to the scientific public for the first time in 1786 as the "chrysolites" of TÃÆ'½n nad Vltavou in a lecture by Josef Mayer of the University of Prague, read at the Bohemian Society of Scientific Meeting (Mayer 1788). Zippe (1836) first used the term "Moldavite", derived from the river Moldau (Vltava) in Bohemia (Czech Republic), from where the first pieces represented coming.
Maps Moldavite
Origin
In 1900, F. E. Suess pointed out that gravel-sized moldavites show strange pitting and wrinkles on the surface, which can not be caused by water action, but are similar to the characteristic markings on many meteorites. He associates matter with cosmic origin and regards moldavit as a special type of meteorite which he proposes a tektit name. Due to their difficult flexibility, very low water content, and chemical composition, the current consensus among earth scientists is that moldavites formed about 14.7 million years ago during the impact of giant meteorites in the current NÃÆ'¶rdlinger Ries crater. Splatters of materials that are melted by impact are cooled when they are completely airborne and most of them fall in Bohemia. Currently, moldavites have been found in areas that include southern Bohemia, western Moravia, Cheb Basin (northwestern Bohemia), Lusatia (Germany), and Waldviertel (Austria). Analysis of the isotope of moldavite samples has demonstrated a composition of 10-beryllium isotope similar to that of Australasia (australites) tektites and Ivory Coast tektites (ivorites).
Ninety-nine percent of all moldavite findings come from the South Bohemian region, one percent found in the South Moravia region. Only dozens of pieces are found in the Lusatian area (near Dresden), the Cheb Basin (Western Bohemia) and Northern Austria (near Radessen). The principal occurrence of moldavites in Bohemia associated with Tertiary sediment from eskÃÆ' Â © Bud? Jovice and T? Ebo? Basins. The most prominent areas are concentrated in the NW-SE strip along the west margin of the eskÃÆ'Â © Bud? Jovice Basin. The majority of these events are tied to VrÃÆ'¡b and Koroseky Sandy Gravel members. A prominent locality in T? Ebo? The basin is tied with gravel and sand formation DomanÃÆ'n.
In Moravia, the occurrence of moldavite is limited to the area bounded by the city of T? EbÃÆ' ?, Znojmo and Brno. The color of moldavites of Moravia is usually different from their Bohemian counterparts, as it tends to be brownish. Considering the number of pieces found, the area of ​​Moravianus is far less productive than that of Bohemian; However, the average weight of moldavites found is much higher. The oldest moldavite-bearing sediment (primer) lies between Slavice and T? EbÃÆ'?. The majority of other areas in southern Moravia are associated with the Miocene sediments and also the Pleistocene river that flows in this area more or less to the southeast, similar to the flow of Jihlava, Oslava and Jevi? Ovka right now.
Properties
The chemical formula of moldavite is SiO 2 (Al 2 O 3 ). Its properties are similar to other types of glass, and reported Mohs hardness varies from 5.5 to 7. Moldavite can be transparent or translucent with mossy green color, with circles and bubbles highlighting the appearance of morphia. Moldavites can be distinguished from green glass imitations by observing the inclusion of their worm-like from lechatelierite.
Use
The total amount of moldavite spread worldwide is estimated at 275 tons.
There are three levels of moldavite: high quality, often referred to as museum class, medium quality and regular class. All three values ​​can be told apart by their appearance. Ordinary class pieces are usually darker and more saturated in their green color, and the surface is seen as a near hole or weathering. These types sometimes appear to be separate from larger pieces.
The museum level has a different fern-like pattern and is much more transparent than the regular class. There is usually a considerable price difference between the two. High quality moldavite stones are often used for handmade jewelry.
There is a moldavite museum, Muzeum VltavÃÆ'n ?, in? EskÃÆ'½ Krumlov, Czech Republic. The Moldavite Association was founded in Ljubljana, Slovenia in 2014. The association examines, exhibits and promotes moldavite and other tektites worldwide and has geologists from more than 30 countries around the world.
References
Article ini menggabungkan teks dari publikasi sekarang di domain public: Ã, Chisholm, Hugh, ed. (1911). "Moldavites". EncyclopÃÆ'Â|dia Britannica . 18 (edisi 11). Cambridge University Press. p.Ã, 652
- J. Baier: The Origin and Importance of Ries Ejection Products for the Impact Mechanism . - Jber. Sarung tangan. oberrhein. geol. Ver., N.F. 91, 9-29, 2009.
- J. Baier: The Ejection Products of the Ries Impact, Germany , the
, Vol. 162, Munich, 2007. ISBNÃ, 978-3-86544- 162-1
Tautan eksternal
- Moldavite museum (Muzeum Vltav? n ?, di? esk? Krumlov, Republic of Ceko)
Source of the article : Wikipedia
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