Chalk It is formed in the sea by sub-microscopic plankton, which fall to the sea floor and are then consolidated and compressed during diagenesis into chalk rock. Most people first encounter the word "chalk" in school where it refers to blackboard chalk, which was originally made of mineral chalk, since it readily crumbles and leaves particles that stick loosely to rough surfaces, allowing it to make writing that can be readily erased. Blackboard chalk manufacture now may utilize mineral chalk, other mineral sources of calcium carbonate, or the mineral gypsum (calcium sulfate). While gypsum-based blackboard chalk is the lowest cost to
Ant chalk Ant chalk Ant chalk, also known as Chinese chalk or 'Miraculous Insecticide Chalk', is an insecticide in the form of normal looking chalk. It contains the pesticides deltamethrin and cypermethrin. While the active ingredients are legal in the United States, the chalk is not legal there. Labeling often falsely claims the chalk is "harmless to human beings and animals" and "safe to use." Chalks have been found to cause serious health problems and deaths. Packaging, often containing lead-based inks, generally does not list ingredients. Despite its illegal status, "Chinese Chalk" is illegally imported from China and sold in corner stores