Moldavite is a distinct natural glass that formed from a powerful meteorite impact. Its genesis links it to both terrestrial and extraterrestrial forces, setting it apart from other gemstones.
Origin and Formation Process
Moldavite is categorized as a tektite, a type of natural glass created under extreme heat and pressure from a meteorite collision.
This specific event occurred approximately 14.7 to 15 million years ago, forming the Nördlinger Ries crater in southern Germany. The tremendous force of the impact melted terrestrial rock, ejecting the molten material high into the Earth’s atmosphere.
As this molten material traveled through the atmosphere, it cooled rapidly, solidifying into the glassy forms characteristic of moldavite before falling back to Earth.
The primary area where moldavite is found today is the Czech Republic, especially in the South Bohemian and Moravian regions. Smaller quantities have also been discovered in parts of Germany, Austria, and even southwestern Poland, indicating the widespread dispersal of the ejected material. This scattered distribution defines its “strewn field,” a unique geological signature of its formation.
External Characteristics
Moldavite exhibits a characteristic green color, ranging from an olive green to a deeper forest green, sometimes with brownish-green tints. The intensity and hue can vary, influenced by trace elements like iron. Its transparency can range from translucent to more opaque specimens.
A defining external feature is its sculpted or wrinkled surface texture, often described as “worm-like” patterns. This texture results from its rapid cooling during atmospheric re-entry and subsequent etching by natural processes in the soil over millions of years.
Moldavite also presents in various typical shapes, including drops, spheres, dumbbells, discs, and irregular fragments. These forms, along with its vitreous luster, contribute to its distinctive appearance.
Chemical Makeup and Internal Features
Moldavite’s chemical composition primarily consists of silicon dioxide (SiO2), similar to quartz, but also includes varying amounts of aluminum oxide (Al2O3) and iron oxide (Fe2O3), along with other trace elements.
Its structure is amorphous, meaning it lacks a defined crystalline arrangement, which is characteristic of natural glass. This is a direct result of the rapid cooling process it underwent.
Internally, moldavite contains elongated gas bubbles, which are trapped air pockets from its rapid solidification. Another significant internal indicator is the presence of lechatelierite inclusions, which are pure silica glass strands formed at extremely high temperatures.
Moldavite has a hardness of 5.5 to 6 on the Mohs scale, a density typically around 2.3 to 2.4 g/cm³, and a refractive index ranging from approximately 1.47 to 1.54.
Authenticity Indicators
Authentic moldavite displays a unique sculpted surface texture, which is not smooth or overly uniform. This natural etching is a result of its formation and prolonged interaction with its environment.
The presence of visible gas bubbles, often elongated or teardrop-shaped rather than perfectly round, is another strong indicator of authenticity. Additionally, genuine moldavite may contain lechatelierite inclusions, which appear as wavy, translucent streaks.
Conversely, caution should be exercised with pieces that exhibit overly bright or unnaturally uniform green colors, a lack of surface texture, or an absence of internal inclusions, as these are common characteristics in manufactured imitations. Sourcing moldavite from reputable dealers who can verify its origin is a practical way to ensure authenticity.