Minerals and Metals in Ancient India v1.c11.s10.6

v1.c11.s10.6

The prevailing colours of the potteries are red of salmon, and these are due to the presence of iron compounds in the clay. The pottery is sometimes covered with a slip of bright red colour due to ferric oxide or painted with designs in black or chocolate which owe their colour to manganese oxide. The red slip is prepared by levigating red ochre or *multānī miṭṭī* (a yellow ochreous earth) with water and employs a maganiferous haematite for the black or chocolate shades. The manganese ores which are frequently associated with ferric oxide impart a pure black colour when rich in manganese, but chocolate when the proportion of iron preponderates.