IVORY BLACK, a high grade carbonaceous black sometimes prepared by carbonizing ivory turnings and cuttings, but more often made by the calcination of bone, only the best grades of product being selected. It should have a deep black, velvety tint. It is largely composed of mineral matter, from 65 to 84% being calcium phosphate with some calcium carbonate. Ivory black is
used by copper-plate printers in preparing their inks, and also to a decreasing extent as a decolourizing agent.