Moldavite - Chlum, Czech Republic
 
Color-intensive moldavite with particularly good clarity and an aesthetic shape. In color as well as luster and shape, this 12.9 cm piece is a wonderful example of natural glass.
 
The formation of moldavites is explained as follows:
Der etwa 1,5 km große Meteorit trat mit etwa 20 km/s in die Erdatmosphäre ein und bildete den Crater, now referred to as Nördlinger Ries . Immediately before the impact, the Erdreich was extremely compacted, the rock melted under high pressure and temperatures and was partially ejected in the plasma state at several kilometers per second. The flat steering angle played a role here. Interactions and degassing took place in the ejected material, which explains the different element contents and typical shapes.[1] During the flight, the material cooled down rapidly and therefore solidified glassy (amorphous). The moldavites are chunks of glass, they were transported above the dense layers of the atmosphere between 250 and 450 kilometres and mostly fell back to the ground in today's Czech Republic. (Source: Wikipedia)