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.
Contra dances were fashionable in the United States and were considered one of the most popular social dances across class lines in the late 18th century, though these events were usually referred to as country dances until the 1780s, when the term contra dance became more common to describe these events.