Slate

ardoise

(piece of such stone used as a tile for flooring, roofing, etc.; such tiles collectively; material from which they are made)

ardoise

(piece, originally of certain types of stone and now of other materials, often in a frame, used for writing on)

ardoise

(record of money owed)

ardoise

(fine-grained homogeneous sedimentary rock)

ardoise

(bluish-grey colour of most slate — see also blue-gray, slate blue, slate gray)