(A) Traditionally, the black keys were made from ebony and the white keys were covered with strips of ivory, but since ivory-yielding species are now endangered and protected by treaty, plastics are now almost exclusively used.

(B) Piano keys are generally made of spruce or basswood, for lightness.

(C) Spruce is normally used in high-quality pianos.

(D) Also, ivory tends to chip more easily than plastic.