Minerals and Metals in Ancient India v2.c44.s6.t2.15

v2.c44.s6.t2.15

The vitriols ranging from blue copper sulphate to green ferrous sulphate were variously known as *tutthaka*, *sasyaka* and *kāsīsa*. *Rājāvarta* mentioned as a *rasa* has been translated as lapis lazuli, a rare gem coloured blue; it could actually be a blue copper mineral.