Natural cornelian is a red variety of chalcedony which is cryptocrystalline quartz. Its red colour is due to the presence of iron impurities in the form of iron oxide or hematite. It can vary from a flesh red to a clear red. It is usually cut as cabochons, or into beads, and is also used for intaglios and cameos.
00000Most of the cornelian in use today is made by staining  agate.

Location - India, China, Colombia, Saxony, Scotland, West Germany and USA.