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Moldavite Informations
 



- Origin:
 
Moldavite is one of the rarest material on earth! It is a natural glass which is made by a huge meteorite impact in central Europe about 14,2 million years ago.
 
 Some detailes about the origin of Moldavites are still unknown but most of the scientists agree that Moldavites are no meteorites. Their chemical composition fits to the first sedimentary layers in the mother crater. No typical elements known from meteorites are enriched in the Moldavite glass. Against many writers who like to sell Moldavites as meteorites, the facts show that it is a product of the fusion of a meteorite with the earth.

A truly starborn gem which is materialised cosmic energie.

- The Impact
 

Before the actual impact happened, at the very first touch of the meteorite, a extremly hot ray of rocksteam shot out of the crater. It was a extremly fast plasma in that the ionised atoms find an unique way to reorganise. This Material condnsed to fluid drops during the flight from the crater to the east. These drops fell still hot in their strew-filds in Czech Republik down.


Ries Meteorite crater, South Germany
Impakt

The meteorite hitting the Earth in south Germany about 14,2 Million jears ago had an estimated size of 1000m !

Impakt

Using mathematic and physikal models, its weight is calculated to 500 Million tons. And it's speed to 20 km/secound by entering the Earthatmosphere (that's 90 000 km/h).

Impakt

Because of two different shockwaves runing trough the Meteorite at the same time, the Meteorite itself collaps and explode just a few 10ths of secounds after the impact.

Impakt

The enourmes ammount of energy during the impact of the Moldavite impact was equivalent with 50 000 atomic bombs!

Impakt

The explosion in the Ries crater threw giantic blocks of rocks (hundrets of times bigger than the big ones in Stonehenge) far out of the crater.

Impakt

The result was one of the bigges Meteorite crater in Europe. And a huge ammount of impact rocks including the Moldavite glass.


 
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- Classification:
 
Moldavite is mineralogically classified to the group of Tektites [Greek: 'tektos' = molten]. Moldavite is the only translucent Tektite with beautiful shades of green. All other Tektites are brownish dark.

Impact Rocks --> Impact Glasses --> Tektites --> Moldavite

 There are only a few places in Czech Republik where Moldavites can be found. Most of them are in a region of the valley of the river Moldau. That's why they are called Moldavites.


 
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- History:

 
In the year 1786 Moldavites are mentioned for the first time by professor Josef Mayer from the university of Praque as "Crysolithen von Thein".

First time scientificaly mentioned in 1786.
Moldavites are found and recogniced by the local geologists but not understood. Many of them thought it was a dump product former glass industries. (Southern Bohemia was famous for an old tradition of glass manufacturers). Moldavites are called Bouteillen Stone (= bottle stone).
 
Others thought of a vulcanic origin because of their glass structure and called them Chrysolith, Pseudochrysolith or Bohemian Obsidian. The problem was that there is no link between Moldavites and their geological surounding.
 
  It was recogniced at the end of the 19th century that Moldavite is natural substance.

 At the beginning of th 20th century Moldavite was used as a gemstone in jewellery. But some of the Czech gemcutters used wine bottels instead of Moldavites for cutting. After a few years the market realised the fakes and Moldavite disapeared from the market again.
 
  The theory about the volcanic origin of Tektites and Moldavites was common until the middle of the 20th century.
 
  1959 Moldavites and the Tektites from Ivory Coast are corelated to their estimeted crater. Genter and Zähringer, two German Geochemists used the K-Ar-method for dating.
 
  1961 two american mineralogists proofed the Ries structure in south Germany as a meteorite impact crater.
 
  John A. O'Keefe links 1976 the Tektites to vulcanic rocks from the moon. He based his idea on the similar chemical composition. But his theory never broke through.
 
  Vladimir Bouska wrote hundrets of papers and handouts about Moldavites what made him to the maim Moldavite expert. He and most of all other geoscientists accept the prooved origin of Moldavites and Tektites as products of an meteorite impact.


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- Occurrence:

 
For meteorites, tektites and Moldavites the sites of occurrences are called strew-fields. The Moldavite strew-field is known as the "Central European Strew Field".

  Almost all Moldavites occur in two seperate areas in Czech Republik. These sub strew-fields are the Southern Bohemian Strew-Field and the Southwestern Moravian Strew-Field. Nowadays 98% of all Moldavite finds are in south Bohemia. With "Ceske Budejovice" in the center of the region.
 
  There are very few places near "Cheb"

Southern Bohemia
Southern Bohemian Strew-Field

in north Bohemia, in north Austria and in the German "Lausitz" area were Moldavites can be found outside the main strew-fields. It is not clear if one or all of these exeptions are geologicaly transported out of the main strew-fields. Or if they represent seperate, small sub-fields.
 


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- Hunting for Moldavite:

 
Collecting and digging for Moldavite is illegal in the Czech Republik! There are a few exeptions for scientists and locals who have a permission.

Moldavites had been traditionally digged for many years. In the early days they were mostly collected from the fields after ploughing.  

Foto
"Tree-hole" in South Bohemia:
dangerous, ugly and illegal!

The Moldavite bearing sediments are occuring at the surface and can go down to 12m. So the local people started to dig. Here they found the "fresh" Moldavite with the typical surface and not damaged by the plough. In the Vrabce gravel pit the collectors used to wait in front of the conveyorbelt with the right size of gravel for a Moldavite to apear. Nowadays most Moldavite localities are closed or like Vrabce completly gone. Some diggers went to deep and terrible accidents happend. After people died in holes, the digging became illegal.

Black digging destroys the countryside and woods and the left holes are ugly and dangerous for wildlife. The local authorities check the known ariers frequently. It is mostly tolerated to search the fields without digging. The best time is after a havy rain with the sun from the back. But please respect the growing periods of the fields. Spring or autum is the season here for collecting.


 
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- Chemical composition:

 
wt %
SiO2
Al2O3 FeO MgO CaO Na2O K2O MnO Ti2O
Bohemian Srtew-Field 79,98-83,20 9,45 1,62 1,92 2,49 0,36 2,89 0,08 0,32
Moravian Srtew-Field
79,26
10,86 2,18 1,31 1,43 0,54 3,39 0,07 0,40

 
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- Physical properties:

 
- Density of Moldavite
 
The density of Moldavites was mostly determined as bulk density of original specimens. It ranges between 2,30 and 2,40 g/cm3. The range of the density of all Tektites is 2,30 to 2,51 g/cm3 As compared with the density of all Tektites the Moldavite is the lightest at all.
 The density decrease with increasing SiO2 content while the contents of elements of relatively higher atomic mass simultaneously decrease.
 
- Hardness of Moldavite
 
According to the Mohs scale of hardness the Moldavite ranges between 6,5 and 6,9. The usual hardness for natural glasses is only 5,5. The SiO2 content rises with increasing hardness and the color of Moldavite is continiously brighter. That's one reason why the light color Moldavites are the best type for gemcutting.
 
- Melting point of Moldavite
 
Moldavite glass melts very slowly between 1200 and 1400 0C
 
- Refractive index of Moldavite
 
The refractive index of tektites ranges between 1,478 and 1,530, the lowest being in Moldavite between 1,478 and 1,510. The average values of the refractive index and comparably also their densities are higher for Moldavite from localities in Bohemia and lower for Moldsavite from localities in Moravia. An indirect dependence of the refractive index and density on the silica content in Moldavites. Lechatelerite in Moldavites has the lowest refractive index and also density among all the solid particles occuring in them.

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Books:
 
- MOLDAVITES The Czech Tektites
- Moldavite starborn stone of transformation