This substance is sulphate of lime or gypsum of a white or delicately tinted colour. It is one of the softest minerals known to nature and is therefore used as an ornamental stone in sculpture, though only for internal work as it weathers easily. It is especially popular in Italy, its country of origin (Volterra, Tuscany).

It is very porous and easy to colour, but too fragile to be a worth- while investment.