Moldavite () is a forest green, olive green or blue greenish vitreous silica projectile glass formed by a meteorite impact in southern Germany (Nördlinger Ries Crater)[ Earth Impact Database: Ries at www.passc.net/EarthImpactDatabase, Accessed 5 February 2018] It is a type of tektite and a gemstone.
Early studies
Moldavite was introduced to the scientific public for the first time in 1786 as "chrysolites" from Týn nad Vltavou in a lecture by Josef Mayer of Prague University, read at a meeting of the Bohemian Scientific Society (Mayer 1788). Zippe (1836) first used the term "moldavite", derived from the
Vltava (Moldau) river in
Bohemia (the
Czech Republic), from where the first described pieces came.
[ "Moldavite" at Mindat.org, Accessed 5 February 2018]
Origin
In 1900, Franz Eduard Suess pointed out that the
gravel-size moldavites exhibited curious pittings and wrinkles on the surface, which could not be due to the action of water, but resembled the characteristic markings on many meteorites. He attributed the material to a cosmic origin and regarded moldavites as a special type of meteorite for which he proposed the name of
tektite.
[J.A Philpotts; W.H Pinson New data on the chemical composition and origin of moldavites. Geochimica et Cosmochimica Acta,Volume 30, Issue 3 (1966) Pages 253-266] Based on an analysis of 23 Bohemian and Moravian samples, in 1966 it was theorised that variations in their composition derived from fractional volatilization, and were not similar in origin to sedimentary or igneous rocks. Values were reported for a range of attributes: oxides, densities, and refractive values index.
In 1987 it was recognised that moldavites were created following meteor impact which melted material and launched it into the air. As the material was airborne, it cooled and solidified. However, the plasma-like vapor at the impact site separated primary melt droplets from other residual vapour. The former then cooled into moldavite.
[W.V Engelhardt; E Luft; J Arndt; H Schock; W Weiskirchner Origin of moldavites. Geochimica et Cosmochimica Acta,Volume 51, Issue 6 (1987) Pages 1425-1443] In 2019 the first LIBS (Laser Induced Breakdown Spectroscopy) study on two typical moldavite samples, followed by routine EPMA (Electron Probe Microanalysis), indicated agreement with EPMA studies and also revealed siderophile elements (Chromium, Iron, Cobalt and Nickel).
[Abhishek K. Rai; Jayanta K. Pati; Rohit Kumar Spectro-chemical study of moldavites from Ries impact structure (Germany) using LIBS Optics & Laser Technology, Volume 114 (2019) Pages 146-157]
Moldavites' highly textured surfaces are now known to be the result of pervasive etching by naturally occurring and humic acids present in groundwater.
Most moldavites are from South Bohemian localities, with just a few found in South Moravian localities. Rare moldavites have been found in the Lusatian area (near Dresden), Cheb basin area (West Bohemia) and Northern Austria (near Radessen), with a few examples found in Southwestern Poland (Lower Silesia) which are thought to have been transported from the Lusitanian sub-strewn field.
In Moravia, moldavite occurrences are restricted to an area roughly bounded by the towns of Třebíč, Znojmo and Brno. The colour of Moravian moldavites usually differs from their Bohemian counterparts, as it tends to be brownish. Taking into account the number of pieces found, Moravian localities are considerably less productive than the Bohemian ones; however, the average weight of the moldavites found is much higher. The oldest (primary) moldavite-bearing sediments lie between Slavice and Třebíč. The majority of other localities in southern Moravia are associated with sediments of Miocene as well as Pleistocene rivers that flowed across this area more or less to the southeast, similar to the present streams of Jihlava, Oslava and Jevišovka.
Properties
The chemical formula of moldavite is SiO
2(+Al
2O
3). Its properties are similar to those of other types of glass, and reported Mohs hardness varies from 5.5
[ to 7.][ O'Keefe A., John. "Tektites and their Origin"., Goddard Space Centre, NASA. Retrieved 9 December 2017.] Moldavite can be transparent or translucent with a mossy green color, with swirls and bubbles accentuating its mossy appearance. Moldavites can be distinguished from most green glass imitations by observing their worm-like lechatelierite, a silica glass, amorphous SiO2, non-crystalline mineraloid, and flow marks schlieren.
Use
Moldavites were discovered by prehistoric people in the Czech Republic and Austria and were used to make flaked tools. Some of the worked moldavites date to the Aurignacian period of the Upper Paleolithic, approximately 43,000 to 26,000 years before the present.
In the modern world, moldavites are often used, rough or cut, as semi-precious stones in jewelry. They have purported metaphysical qualities and are often used in crystal healing. The price of moldavite specimens has been rising in recent years in particular because of its increasing popularity for metaphysical uses.
Presentation
There is the Moldavite Museum in Český Krumlov, Czech Republic.
==Gallery==
Further reading
-
Milan PRCHAL "60 years on the green wave". (Robert Jelinek, Admir Mesic Eds). Der Konterfei 072, Vienna, 2021.
-
The Austrian Moldavite – On the Traces of the Green Tektite (Robert Jelinek Ed.). Der Konterfei 078, Vienna, 2023.
External links
