What is a mountain made out of?

Answer 1

A mountain is made of, quite simply, earth. Mountains form where land has been forced upwards by pressure from the tectonic plates, and so they are made of much the same thing that regular land is made of (such as rock and minerals).
Earth and rocks

Answer 2

Mountains are made up of a combination of rocks, minerals, and soil that have been compressed and uplifted from the Earth's crust. The three main types of rock in mountains are igneous, sedimentary, and metamorphic, which have been reshaped by tectonic forces such as plate movement, folding, and faulting. Over time, erosion can also shape and expose the underlying rock formations in mountains.