Olivine has the formulae (Mg,Fe)2SiO4 and a relative hardness of 7. It's name is derived from the characteristic olive green colour. A common rock forming mineral. A clear green variety is called peridot and has some uses as a gem.
Hear it on YouTube. Here's a piece that many people know, and rightfully so! This famous classical piece from the romantic period is one of those pieces that has the ability to make anyone feel happy. Composed in the 1920s, for a ballet, the piece was an instant success.
The great Romantic ballerinas were idolised throughout Europe. Marie Taglioni (1804 - 1884) danced in Paris, St Petersburg, London and Italy and Fanny Elssler (1810 - 1884) even toured North America. The rivalry between Elssler and Taglioni and their supporters was intense although they had very different styles.