Chalk

A powdery residue on the surface of a material.

Merriam-Webster Online Dictionary
chalk (noun)
1.
a) a soft white, gray, or buff limestone composed chiefly of the shells of foraminifers
b) a prepared form of chalk or a material resembling chalk especially when used (as for writing on blackboards) as a crayon
2.
a) a mark made with chalk
b) British a point scored in a game
chalk (verb)
transitive verb
1.
to write or draw with chalk
2.
to rub or mark with chalk
3.
a) to delineate roughly - sketch
intransitive verb
b) to set down or add up with or as if with chalk - record usually used with up chalk up the totals to become - chalky the paint had begun to chalk