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Home | Exhibitions | Barocci: A lesson in drawing | Barocci Drawings: MediaBlack chalk is carbonaceous shale made mainly of graphite minerals or other amorphous carbons. It is a dry drawing medium. Cennini describes its qualities and mentions that it was found in Piedmont. It was extensively used in Italy from the second half of the 15th century because it was suitable both for making thick lines for large-scale drawings and thin lines on smaller sheets.