Amber is fossilized tree resin, which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. The composition of amber leads to the general formula C10,H16,O. Amber occurs in a range of different colors. Uncommon colors include red amber (aka "cherry amber"), green amber, and blue amber. The rarest is blue amber. It turns blue in natural sunlight and any other partially or wholly uv light source. In long-wave UV light it has a very strong reflection, almost white. Only about 100 kg is found per year, which makes it valuable and expensive.