Moldavite is a unique, translucent green material that has captured the imagination of collectors and scientists due to its unusual appearance and high market value. Its striking color and sculpted surface often lead to speculation about an extraterrestrial origin. The scientific answer involves a dramatic event that links Earth and the cosmos, but the material itself is not purely from outer space.
What is Moldavite
Moldavite is scientifically classified as a natural glass, placing it in the category of mineraloids rather than true minerals, since it lacks a crystalline structure. It is a member of the tektite group, which are glassy objects formed by the impact of large meteorites on Earth. The typical color is forest to olive green, though shades can range to brownish-green.
The material is primarily composed of silicon dioxide (silica), with traces of aluminum oxide and a very low water content, characteristic of materials formed under extreme heat. Moldavite’s most distinctive feature is its surface texture, known as sculptation, which consists of complex pitting, wrinkles, and grooves. This texture was created both by its aerodynamic travel through the atmosphere and by millions of years of chemical etching by groundwater.
Answering the Space Origin Question
The direct answer to whether Moldavite is from space is no; it is not a meteorite or a fragment of the impacting space object. Moldavite is a product of a massive cosmic event that occurred on Earth. Scientific consensus identifies Moldavite as terrestrial rock that was instantly melted and ejected during a hypervelocity impact.
The rock was sourced from Earth’s crust at the impact site and transformed by the immense heat and pressure generated by the collision. The material itself is Earth-based, but its formation was directly catalyzed by an extraterrestrial impactor. Moldavite’s chemical composition, including its ratio of isotopes and trace elements, closely matches the sedimentary rocks found in the region of the impact.
The Science of Impact Glass Formation
The formation of Moldavite began approximately 14.7 to 15 million years ago with the collision of a large body, likely an asteroid, traveling at immense speed. The impactor struck the surface at a velocity estimated to be around 20 kilometers per second, generating extreme shockwaves and temperatures. This energy instantly vaporized and melted the surrounding silica-rich surface rock.
The molten material was then explosively launched high into the atmosphere as a superheated spray of liquid glass droplets. As these droplets traveled through the air over hundreds of kilometers, they cooled rapidly and solidified into an amorphous glass structure before falling back to Earth. The high-speed flight and cooling process is responsible for the aerodynamic shapes, such as teardrops, discs, and spheres, unique to tektites.
The Ries Crater and Geographic Distribution
The event that created Moldavite is traced to the Nördlinger Ries structure in southern Germany, a large impact crater approximately 24 kilometers in diameter. This impact also created the smaller, nearby Steinheim crater. The estimated age of this impact, and thus the age of Moldavite, is about 14.7 million years, placing it in the Miocene epoch.
Despite the impact site being in Germany, the vast majority of Moldavite specimens are found hundreds of kilometers away in the Bohemian strewn field. This area covers parts of the Czech Republic, primarily the Bohemian and Moravian regions, with smaller amounts found in Austria and Germany. The oblique angle of the impact and the trajectory of the ejected material explain why the glass rained down primarily over the Czech Republic, far from its point of origin.