Moldavite is a green tektite. A tektite is an impact glass, created due to the impact of a meteorite with the earth's crust. It is believed that the meteorite that created the Ries Kessel (a massive 15 mile diameter crater), 120 miles away in Germany "splashed," hot material into the atmosphere that cooled as it fell back to Earth. This impact material, landed across a relatively small (10 to 15 square mile) area in the current Czech Republic. This impact event is dated around 15 million years ago. Moldavite miners must dig holes to access this old layer in which the Moldavite is found. Moldavite is typically quite small, with the largest pieces generally available, weighing between 30 to 50 grams (up to 6-7 cm long). Moldavite is valued for its size (larger pieces are much rarer), condition (lack of damage), an attractive green color, and how textured, or "spikey," the surface is. 

This one has a beautiful rich green color, and a well textured surface. When I buy Moldavite I typically buy at least a kilo at a time from the miners. This was one of the best for its size from a recent purchase. There are two micro chips that are only seen if studied closely and don't amount to anything (so hard to spot). It weighs 15 grams.