Beryl is a fairly common and widespread mineral and is the main raw material for the extraction of beryllium, a chemical element which is used in industry to harden metal alloys. Its crystals usually consist of a hexagonal prism and are almost colourless, with faint bluish green and light-yellow colours. There are two varieties which are most sought after as gems: aquamarine and emerald. The first, aquamarine, has a very light greenish-blue colour, reminiscent of the colour of the sea, as its name suggests. The second, emerald, has a wonderful intense green colour.
The first reports of tourmaline seams in Elba date back to 1825. The crystals form in a variety of colours from aquamarine to pink and honey yellow. To date, 20 different forms of beryl have been identified on Elba.
An unusual variety of beryl which can be found on Elba is Rosterite, which is characterised by the presence of cesium, with colourless or pale pink crystals.