(n) :
any bright-coloured kind of chalcedony apart from cornelian; an opaque, impure variety of quartz, of red, yellow, and other dull colors, breaking conchoidally with a smooth surface
(n) :
any bright-coloured kind of chalcedony apart from cornelian; an opaque, impure variety of quartz, of red, yellow, and other dull colors, breaking conchoidally with a smooth surface