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Delve into the fascinating origin of the famous, fiery tektite found scattered across the Czech Republic, Austria and Germany.
A Cosmic Tale of Fire and Diamonds
Let’s embark on an intriguing geological tale, delving into the captivating journey of moldavite. Unlike typical stones and crystals which emerge from deep within the Earth’s crust, moldavite has a unique origin — it was born from above. Picture this: 15 million years ago, a large asteroid collided with Earth, unleashing a sudden, spectacular burst of violent energy which resulted in the formation of moldavite…
So, how exactly did this colossal celestial collision create our beloved and delicate moldavites? The answer lies within tektite formation. Tektites (including moldavites) are formed upon an impact when pieces of silica-rich sediment and grit from the Earth’s surface are ejected up into the atmosphere at incredible speeds, vaporising instantly into molten droplets. These pieces rapidly cool and solidify as they fall back to Earth, and our distinctive glassy tektites are born – witnesses to the violent forces at play during an impact event.
The Birth of Moldavite: A Cosmic Collision
Moldavites were formed around 14.7 million years ago during the Miocene period – a warm and sleepy episode in geological time, when primitive antelope, giraffe and deer roamed the quiet grasslands and damp forests of Europe. This peace was shattered when a huge asteroid measuring almost 1.5km-wide struck Miocene-Germany at a mind-bending speed of 20 kilometres a second – an enormous event which ejected material from the impact site as far as 450km away. The huge crater which still remains today is known as the Nördlinger Ries crater, spanning almost 24km across. As the asteroid struck theEarth’s surface from a south-westerly aspect, the spray of ejected material fans north-east of the impact site, and moldavites are found today across Austria and the Czech Republic. This scattering of green droplets is known as the Central European strewn field. (see Fig. 2).
The Geological Legacy of Moldavite
Geologically speaking, moldavite is a relative newcomer, with an age of approximately 14.7 million years. This might not sound very young – and indeed in human terms, it’s not – but geologists frequently deal with timescales spanning all the way from the start of Earth’s lifetime, 4.3 billion years ago, with many geological formations dated to hundreds of millions of years old. Comparatively speaking, moldavite is a baby.
Moldavite’s distinctive glassy composition is due to the very rapid cooling it underwent during formation. Most crystals grow slowly over great geological time (thousands, or more often millions of years), which allows their molecular structures to build carefully and gradually into the familiar, organised habits we see in crystal points and druzes. This organised, repeating,and slow-forming pattern is known as a crystal lattice. Tektites are born in a much faster process: molten droplets of SiO₂-rich (silica) sediment undergo cooling almost instantaneously as they fall back to Earth, meaning the silica molecules within the crystal have no time to organise themselves and remain ‘amorphous’ and jumbled up. The result is a glassy material, with no true crystal habit. This is why moldavite is strictly classed as a mineraloid, and not a mineral or crystal – as by definition, minerals must have an organised structure, which tektites do not. (See Figure above.)
Moldavite is not the only captivating ‘crystal’ born from the Nördlinger Ries impact. By complete chance, a graphite deposit lies within the Reis crater. When this carbon-rich material was superheated and compressed during the impact, tiny diamonds were formed. The German town of Nördlingen is built from this material, and is known locally as the ‘Town of Diamonds’, with glittering stone stairs and walls peppered with diamonds only a few nanometres wide.
Moldavites Colouring and Appearance
A large part of moldavite’s popularity is encouraged by its unusual appearance – high quality material exhibits distinctive furrows and surface etching, with stunning colour ranging from brownish, forest, and olive, through to an acrid blueish ‘poison’ green. Etching has occurred over the last 14.7 million years whilst acidic groundwaters and soils have eaten into the exterior of buried moldavite pieces. Their colouring is due to impurities of aluminium and iron oxide, and material from different localities within the Czech Republic and Austria can be identified and differentiated by colouring and differences in etching and appearance, so forming sub-families within the strewn field, or sub-strewn fields.
Mining Moldavite: Controversy and Conservation
Today, moldavite mining has become a lucrative industry, driven by a persistent online buzz. Moldavite shot to viral fame on social media in 2020, and the cost price for genuine material skyrocketed in a very short period of time – from 10-20p per gram, to anywhere between £30 and £300 per gram. However, the environmental impact of moldavite mining operations remains a subject of debate. Moldavite – or ‘vltavín’ as it is known to older Czech finders – is harvested by hosing-down the forest slopes in which the material is found (search for ‘moldavite farming’ on YouTube). This action essentially washes away the surrounding soils and clays, leaving the moldavite pieces to be spotted and extracted. While the extraction of moldavite provides a valuable income for ‘hunters’ – the average Czech income is considerably lower than those in Germany or Austria – there is a controversy around the scars this process leaves on the landscape, with many Czech-national vltavín hunters resorting to selling their personal collections due to dwindling supply as the moldavite boom runs to an end.
Moldavite Fakes and Frauds
This imbalance in limited supply and huge demand has of course spawned a significant volume of inauthentic material. Fake Moldavite is a common scam, and buyers should be wary of suspiciously low prices, synthetic bright green colouring, and smooth, ‘wet-looking, surface etching. Recently publicised fakes have famously included etched and tumbled fragments of green beer bottles. Moldavite sellers and wholesalers should be able to provide sourcing authentication if asked – although many seasoned crystal buyers would argue that certificates of origin are proof only of access to a printer. Fake moldavite is especially difficult to identify when cut or polished – such as in jewellery – but phoney moldavite rarely exhibits convincing fluvial structures and internal bubbles. These are both signatures of high-speed travel and rapid cooling undergone through the Earth’s atmosphere – fluvial structures look like greasy, wavy lines suspended within the moldavite glass, and are best observed in polished or cut specimens. If elongated internal bubbles are observed alongside fluvial structures, the material is likely genuine, however buyers should still be on the lookout for suspicious pricing and odd colouring. As the saying goes, if it’s too good to be true…