Moldavite

Key takeaways

Moldavite belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Moldavite to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Moldavite from memory before moving on to harder problems.

Reference excerpt

Moldavite (Czech: vltavín) is a forest green, olive green or blue greenish vitreous silica projectile glass formed by a meteorite impact in southern Germany (Nördlinger Ries Crater) that occurred about 15 million years ago. It is a type of tektite and a gemstone. Material ejected from the impact crater includes moldavite, which was strewn across parts of Germany, the Czech Republic and Austria.

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.

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. 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. 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). Moldavites' highly textured surfaces are now known to be the result of pervasive etching by naturally occurring CO2 and humic acids present in groundwater. Because of their extremely low water content and chemical composition, the current consensus among earth scientists is that moldavites were formed about 14.7 million years ago during the impact of a giant meteorite in the present-day Nördlinger Ries crater. Currently, moldavites have been found in an area that includes southern Bohemia, western Moravia, the Cheb Basin (northwest Bohemia), Lusatia (Germany), and Waldviertel (Austria). Isotope analysis of samples of moldavites have shown a beryllium-10 isotope composition similar to the composition of Australasian tektites (australites) and Ivory Coast tektites (ivorites).

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. Principal occurrences of moldavites in Bohemia are associated with Tertiary sediments of the České Budějovice and Třeboň basins. The most prominent localities are concentrated in a NW-SE strip along the western margin of the České Budějovice Basin. The majority of these occurrences are bound to the Vrábče Member and Koroseky Sandy Gravel. Prominent localities in the Třeboň Basin are bound to gravels and sands of the Domanín Formation. 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 SiO2(+Al2O3). Its properties are similar to those of other types of glass, and reported Mohs hardness varies from 5.5 to 7. 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

References

This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Moldavite". Encyclopædia Britannica. Vol. 18 (11th ed.). Cambridge University Press. p. 652.

J. Baier: Zur Herkunft und Bedeutung der Ries-Auswurfprodukte für den Impakt-Mechanismus. – Jber. Mitt. oberrhein. geol. Ver., N. F. 91, 9–29, 2009. J. Baier: Die Auswurfprodukte des Ries-Impakts, Deutschland, in Documenta Naturae, Vol. 162, München, 2007. ISBN 978-3-86544-162-1

Further reading Milan PRCHAL "60 years on the green wave". (Robert Jelinek, Admir Mesic Eds). Der Konterfei 072, Vienna, 2021. ISBN 978-3-903043-59-6 The Austrian Moldavite – On the Traces of the Green Tektite (Robert Jelinek Ed.). Der Konterfei 078, Vienna, 2023. ISBN 978-3-903043-66-4

External links

Moldavite Museum in Český Krumlov

Illustrations

Worked examples

Example 1 — a first encounter with Moldavite

Start with the simplest possible case. Write down what Moldavite claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Moldavite before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Moldavite ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Moldavite

In research: Moldavite appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Moldavite in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Moldavite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Gemstones, Glass in nature, Impact event minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Moldavite outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Moldavite in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Moldavite means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Moldavite out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Moldavite in simple terms?

Moldavite (Czech: vltavín) is a forest green, olive green or blue greenish vitreous silica projectile glass formed by a meteorite impact in southern Germany (Nördlinger Ries Crater) that occurred about 15 million years ago. It is a type of tektite and a gemstone.

Why does Moldavite matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Moldavite?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Moldavite.