Carnelian is a sub-species of calcedony. Its colours are white yellow, brown, and red. It has a conchoidal fracture, and a spec. grav. of 2.6. It is semi-transparent, and has a glistening lustre. It is found in the channels of torrents in India, in nodules of a blackish olive, passing into grey. After exposure for some weeks to the sun, they are subjected to heat in earthen pots, whence proceed the lively colours for which they are valued in jewellery.