Is common table salt a rock, a mineral, both, or neither?
It is both. It fits the definition of a mineral: naturally occurring, inorganic solid with a definite chemical formula and crystalline structure. It also fits the definition of a rock: naturally occurring solid that forms large deposits in the Earth. There are not many kinds of rock that are made up of a single mineral, making halite (table salt) one of the few minerals that is also a rock.