Moldavite
Last updated: April 2026
Tektite — natural glass formed ~14.8 million years ago by a meteorite impact in the Ries crater (Germany), with ejected melt landing in what is now the Czech Republic. The only gem-quality tektite. Heavily faked with manufactured green glass; genuine moldavite has lechatelierite inclusions and sculptured surface texture.
Moldavite has a specific gravity of 2.35 and a refractive index of 1.480–1.510, with a Mohs hardness of 5.5. It is singly refractive.
Physical & Optical Properties
Measured with a polariscope, a refractometer, a hydrostatic balance, a Chelsea filter, a UV torch, a loupe, a darkfield loupe and a spectroscope — step-by-step for each.
Through the refractometer
Drawn from the refractive index above, on a 1.40–1.81 scale. How to take this reading.
Key Differentiators
- Unique sculptured/etched exterior surface with flow ridges, pitting, and corrosion features
- Lechatelierite inclusions — wispy pure SiO₂ glass threads unique to tektites, absent in man-made glass
- Low SG 2.32–2.38 — lighter than most glass fakes (~2.40+) and most other green stones
- Found ONLY in Bohemia/Moravia (Czech Republic) — any 'moldavite' from elsewhere is fake
- Flow structures (schlieren) and gas bubbles under loupe — no crystalline inclusions possible
Common Simulants
- Manufactured Green Glass: Green glass fakes lack lechatelierite inclusions. Glass fakes typically have higher SG (2.40+), may show mold seams, and lack the organic sculptured surface corrosion of genuine moldavite. Look for lechatelierite under 20–40× magnification — its presence indicates genuine moldavite.
- Green Tourmaline: Tourmaline is crystalline (doubly refractive), RI 1.624–1.644, much higher than moldavite glass (1.48–1.51). SG 3.06. Not isotropic.
- Green Sapphire: Sapphire RI 1.762–1.770 is far higher than moldavite. SG 3.99–4.05. Not comparable on any standard test.
Measurement Guides
Identifying a moldavite? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.
Try Loupewise Free →Studying for the GIA, FGA, or FEEG practical? Moldavite is one of the 132 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
Practice exams →