Carnelian

Carnelian (also spelled cornelian) is a brownish-red mineral commonly used as a semi-precious gemstone.Websters New World College Dictionary. 4th ed. 2001.Duda, Rudolf  and Rejl, Lubos 1990. Minerals of the World. 

Similar to carnelian is a darker and harder stone called 'sard'. The two names are often used interchangeably. Both carnelian and sard are varieties of the silica mineral chalcedony coloured by impurities of iron oxide.

The gemstone has been used since prehistory.Tallon F. (ed) Cornaline et pierres précieuses de Sumer à l’Islam. Musée du Louvre, Paris

 References 

Category:Quartz
Category:Gemstones