Moldavite is a unique natural glass known for its distinctive green coloration and enigmatic origin. This captivating material has drawn curiosity for centuries. Its unusual characteristics hint at a dramatic past, making it a subject of geological interest.
Its Unique Composition
Moldavite is primarily composed of silicon dioxide (SiO2), which is also the main component of quartz. It also contains significant amounts of aluminum oxide (Al2O3), potassium oxide (K2O), and iron oxide (FeO or Fe2O3). The presence of iron is largely responsible for Moldavite’s characteristic green hues, which can range from pale to deep forest green.
Trace elements such as magnesium (Mg), calcium (Ca), and sodium (Na) contribute to its overall chemical makeup. While its composition shares similarities with terrestrial rocks, the specific variations and ratios of these elements are a direct result of its extraordinary formation process. The exact chemical composition can vary slightly depending on the specific location where it is found.
The Cosmic Origin Story
Moldavite formed approximately 14.7 to 15 million years ago as a result of a colossal meteorite impact. This event occurred in what is now southern Germany, creating the Nördlinger Ries crater, which is about 15 miles in diameter. The impacting asteroid was estimated to be at least one kilometer in diameter.
The extreme heat, reaching up to 30,000°C, and pressure generated by the impact melted the surrounding terrestrial rocks, particularly silica-rich sediments. This molten material was then ejected high into the atmosphere, traveling hundreds of kilometers. As the molten glass ascended and then fell back to Earth, it rapidly cooled and solidified, forming the pieces of Moldavite found today across parts of Germany, the Czech Republic, and Austria.
Distinguishing Features of Moldavite
Moldavite exhibits a distinctive green coloration, ranging from transparent pale green to deep forest, olive, or bottle green. Its surface often displays a sculptural and etched texture, characterized by pitting and wrinkles. This unique texture results from its rapid descent through the atmosphere and subsequent natural corrosion within the ground over millions of years.
Internal features also help identify Moldavite, including the presence of gas bubbles. These bubbles formed from gases released from the host rock during the impact and can appear elongated due to cooling during its atmospheric flight. Additionally, genuine Moldavite contains worm-like inclusions known as lechatelierite. Lechatelierite is a high-temperature silica glass, serving as evidence of the extreme heat and rapid cooling involved in Moldavite’s formation.
Moldavite’s Place in the Tektite Family
Moldavite is a specific variety of tektite, natural glass objects formed by meteorite impacts.
While most tektites typically appear black or dark brown, Moldavite stands out as a rare green variety. Its unique green color and gem-quality characteristics distinguish it within the broader tektite family. This distinctiveness arises from the specific geological conditions and chemical composition of the target rocks involved in its formation.