Green Emerald 1 Piece Raw Minerals Stones Rocks Collecting (2)

Green Emerald 1 Piece 21-30 gr - cm 3-5 Raw Minerals Stones Rocks for Collection.
Sorosilicate of Beryllium and Aluminum.

Emerald is a variety of Beryl, characterized by an intense green colour, probably due to the presence of Chromium (up to 0.19%) and possibly Vanadium and Iron.
Only the presence of chromium makes beryl an emerald; beryl in which only vanadium is present should instead be called green beryl.
The word "emerald" comes from the Latin smaragdus, coming from the Greek σμάραγδος (smàragdos), which literally means "green stone".
It is of dimetric crystalline group and hexagonal system. Its chemical formula is equivalent to Be3Al2Si6O18, i.e. beryllium, aluminum, silicon and oxygen together with chromium and/or vanadium.
Usually the genesis is pegmatitic-pnemautolytic. It is typically found in granites or metamorphic rocks (schists).
The oldest deposits are those in Egypt. In Egypt the emerald mines, which were probably already active around 3500 BC, were rediscovered only in 1816. Those of the Urals were discovered only in 1830. The deposits of South America were known in the 16th century: the main ones, and still productive , deposits are those of Colombia (the "Muzo" mine is very famous) and of Brazil. The largest mine in the world is currently that of Santa Terezina in Goias where they are extracted in the open air. The parent rock here is also a schist.