Let us take a look at five of the most commonly used metals and their properties. Iron: Iron is the most commonly used metal in the world, and probably one the most abundant in the earth's crust. It is also one of the metals found abundantly in the human body. Therefore, it also has medicinal uses as well.et us take a look at five of the most commonly used metals and their properties. Iron: Iron is the most commonly used metal in the world, and probably one the most abundant in the earth's crust. It is also one of the metals found abundantly in the human body. Therefore, it also has medicinal uses as well.