Moldavite is an unusual form of naturally occurring glass, technically classified as a tektite. Its formation is linked to a massive meteorite impact that occurred approximately 15 million years ago in Southern Germany, creating the Nördlinger Ries crater. The intense heat and pressure melted local terrestrial rocks, flinging the molten material hundreds of miles through the atmosphere. This rare silica glass subsequently rained down and settled primarily in a strewn field across the Czech Republic, near the Moldau River, which gives the material its name.
The Signature Visual Characteristics
The color of genuine Moldavite typically presents in a narrow spectrum of greens, ranging from pale, yellowish-green to deep, dark bottle green. The most common color is moss or olive green, a hue resulting from iron content within the silica glass. Samples exhibiting a uniform, bright emerald or neon green color should be viewed with suspicion, as they rarely occur naturally.
When held up to light, Moldavite’s transparency varies significantly, from nearly opaque in thicker pieces to highly translucent in thinner fragments. The stone’s form is a direct result of its high-speed flight through the atmosphere while molten. These natural shapes, known as splash forms, include aerodynamic shapes such as drops, discs, rods, and ovals. Pure black samples are uncommon, usually only visible in very thick pieces that appear translucent green when backlit.
Surface Textures and Internal Structure
A defining feature of authentic, unpolished Moldavite is its distinct surface sculpting, a complex texture difficult for manufacturers to replicate. This sculpting consists of intricate pitting, wrinkles, and grooves that developed over millions of years due to natural chemical etching by acidic groundwater and soil. The degree of etching varies by locality; for example, pieces from the Besednice area are known for their sharp, spiky texture, while others may be smoother.
Beneath the surface, the internal structure of Moldavite contains two unique identifiers that distinguish it from common glass. The first is lechatelierite, which appears as fine, wispy threads of pure silica glass. These wires are created when quartz particles melt and stretch under the extreme heat of the impact.
The other distinct internal feature is the inclusion of gas bubbles, remnants of the material’s rapid cooling in the atmosphere. These bubbles are typically small and numerous, often elongated or oval in shape due to the molten glass flowing before solidification. In contrast, bubbles found in manufactured glass are usually fewer, larger, and perfectly spherical.
Spotting Imitations and Fakes
Because of its rarity, the market is frequently flooded with manufactured green glass sold as Moldavite. A major red flag is a surface that appears too glossy or overly smooth, lacking the intricate, naturally etched texture of genuine pieces. Manufactured pieces are often made in molds, leading to a uniformity in shape and size not seen in nature.
Another indication of a fake is an unnaturally bright, uniform color, or a price significantly lower than the market average. True Moldavite has a specific gravity ranging from 2.32 to 2.38, which is slightly denser than most common green bottle glass. While difficult to measure without specialized equipment, a piece that feels too heavy for its size may be synthetic.
Consumers can perform a simple check by examining the piece under magnification with a jeweler’s loupe. The presence of lechatelierite wires and the irregularly shaped gas bubbles is the most reliable way to confirm authenticity in faceted or polished pieces. While some fakes may fluoresce under UV light, authentic Moldavite is inert, meaning it will not glow.