Gem library
Moldavite
Green glass born of a meteorite impact
Moldavite is a natural glass thrown out by an asteroid impact that happened fifteen million years ago in Germany. The molten terrestrial rock came down four hundred kilometres away, in Bohemia, as green drops frozen in mid-flight.
- Hardness (Mohs)
- 5.5 – 6
- Density
- 2.32 – 2.38
- Crystal system
- Amorphous
- Refractive index
- 1.48 – 1.54
- Cleavage
- None
Mineralogical identity
- Family
- Impact glass (tektite)
- Species
- Tektite
- Variety
- Moldavite of Bohemia and Moravia
- Chemical formula
- SiO₂ (75 – 80 %) with Al₂O₃, K₂O, MgO
- Crystal system
- Amorphous
- Classification
- Semi-precious stone
- Rarity
- Very rare
- Indicative price
- €10 – 300/g (sculpted Besednice pieces: far beyond)
Etymology
From the Moldau, the German name of the Vltava, the Bohemian river in whose terraces the first specimens were picked up.
Physical & optical properties
- Hardness (Mohs)
- 5.5 – 6
- Density
- 2.32 – 2.38
- Refractive index
- 1.48 – 1.54
- Birefringence
- none
- Cleavage
- None
- Fracture
- Conchoidal
- Lustre
- Vitreous
- Diaphaneity
- Transparent to translucent
- UV fluorescence
- None
- Pleochroism
- None
- Colours
- green, bottle green, olive green, green brown
Formation, geology & history
A crater in Germany, stones in Bohemia
About fifteen million years ago an asteroid some kilometre and a half across struck what is now Bavaria and dug the Ries crater, twenty-four kilometres wide, still perfectly visible around the town of Nördlingen. The energy vaporised the sands and sandstones of the target; part of the molten matter was ejected beyond the dense atmosphere, cooled in flight and fell as rain three or four hundred kilometres to the north-east, in what is today South Bohemia. The link between the two was established by dating and by chemistry: moldavites have the composition of Ries sediments, not that of a meteorite. So this is not a stone that came from space, it is a terrestrial stone that space threw into the air.
The sculpture of flight
What gives a moldavite its value is its surface. Crossing the air at great speed and then spending millions of years in acid sediments, the glass became hollowed with grooves, wrinkles and cavities of a complexity nothing imitates easily. The Besednice pieces, called «hedgehogs» for their spiny texture, are the most sought after and sell by the piece, not by the gram. Moravian moldavites, browner and smoother, are worth distinctly less. The material is heterogeneous: under a loupe you see flow striae, elongated bubbles and inclusions of lechatelierite, pure silica that had no time to mix.
A resource running out
The strewn field is finite, and it has been combed since the eighteenth century. The most productive Czech deposits are now exhausted or closed, extraction is strictly regulated, and annual production is counted in kilograms. Prices have risen tenfold in twenty years, and counterfeiting has followed: the market is now saturated with moulded green glass made in Asia. Buying a moldavite without knowing how to recognise one amounts, statistically, to buying bottle glass.
How to recognise it
- Elongated bubbles, never roundAt 10×, a moldavite shows bubbles stretched in the direction of flow and parallel striae. Moulded glass has spherical bubbles and a homogeneous mass.
- The texture never repeatsNatural grooves are irregular, of unequal depth, with sharp edges. A moulded surface has rounded hollows, a suspicious regularity, and two pieces from the same batch look alike.
- The colour in transmitted lightAn olive to bottle green, often uneven, with lighter zones. A bright, perfectly uniform apple green is not natural.
Imitations, treatments & confusions
- Moulded green glassThe dominant imitation, made in China and Thailand. Round bubbles, a mould line sometimes visible, a repetitive texture, and a price too low to be true.
- Worked bottle glassBottle bases etched with acid to imitate corrosion. The colour is too frank, and the etch marks are uniform.
- Other tektites sold as moldaviteThe tektites of South-East Asia, black, and the darwinites of Australia, exist and are authentic, but they are not moldavites and they are worth ten times less.
Deposits & origins
Czech Republic (South Bohemia around Besednice, and Moravia: the only strewn field in the world), a few pieces in Germany and Austria
Care & precautions
- Warm water and a soft cloth. The glass does not mind water, but the grooves hold soap.
- No ultrasonics: the inclusions and bubbles create points of failure.
- Never polish it. The natural surface is the whole value; a polished moldavite loses the essential.
- Set it in a closed bezel rather than claws: at hardness 5.5 the edges blunt quickly.
Traditions & crystal healing
- Chakras
- Heart · third eye
- Zodiac signs
- Scorpio · Sagittarius
- Element
- Fire
Lithotherapy has made it one of its most celebrated stones, associated with rapid transformation, with a vocabulary of extraterrestrial origin that does not match what geology says: the matter is terrestrial, it is the impact that was not. Cultural heritage, never medicine.
The virtues described here belong to tradition and cultural heritage. They are in no way medical advice and never replace a consultation.
Frequently asked questions
Does moldavite come from space?
No, and that is the commonest confusion. Its chemistry is that of Bavarian sands; it was the impact of a celestial body that melted and threw it. The celestial body itself was vaporised.
How do I recognise a real moldavite?
The loupe settles it: elongated bubbles and flow striae on one side, round bubbles and a homogeneous mass on the other. Add a surface whose texture never repeats, and a price consistent with the rarity.
Why is it so expensive?
A single strewn field in the world, combed for three centuries, deposits exhausted and extraction regulated. Supply falls every year while demand rises.
Tools for this stone
Moldavite: only the tools this stone actually concerns, each carrying the value read on this page.