Ferrous mineral is a term used to describe a mineral containing IRON. IRON is a chemical element with the symbol Fe and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. IRON is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. IRON is found in many minerals, including magnetite, hematite, limonite, and siderite.