White Chalk
White highlights could be added to red or black chalk drawings, either with calcite (calcium carbonate, or common blackboard chalk), or soapstone (steatite). This was especially effective against blue or buff paper.

White chalk has rarely been used by itself as a drawing material, except by a few artists working on dark or black paper for a striking, even grotesque, effect.
 


François du Quesnoy. Study Sheet. Art Market
 

by Michael Miller
Information supplied by: http://www.nyu.edu/classes