Citrine is called so after the French word, Citron, in reference to it's lemon yellow colour. It is a quartz crystal and somewhat rare. This is partly due to the heating process in nature necessary to create true citrine; some minerals that begin as amethyst are heated naturally by nearby magmatic bodies which causes the change to citrine.
Chemistry~ Si02

Citrine  23 $ 67.00	Citrine  27 $ 48.00	Citrine 29 $  37.00	Citrine  32 $  24.00
Citrine  33 $ 31.00	Citrine  37 $ 23.00	Citrine  39 $  31.00