These smooth chalks from Sargent Art can be used on the blackboard or on pastel paper. They are more highly pigmented than the blackboard chalks and can be harder to remove from the board.
These chalks are labeled Non-Toxic by the manufacturer and conform to ASTM D 4236, but they do contain Titanium Dioxide as labeled on the item.
Box of 12 assorted…Catalog Number 4112…$8.50
Box of 24 assorted…Catalog Number 4124…$13.00
Box of 48 assorted….Catalog Number 4148…$21.00