Quiz: Remember the definition of mal de mer?
a chemical element with properties intermediate between those of typical metals and nonmetals. Usually considered under this classification are the chemical elements boron, silicon, germanium, arsenic, antimony, and tellurium. The rare elements polonium and astatine are also sometimes included. Most of these elements are important industrial materials, being used to make transistors and other semiconductor devices, ceramics, solar batteries, and certain polymers.