"Ferrous iron" refers to iron that exists in a particular chemical state that is easily absorbed by our bodies. It is a form of iron that we need to stay healthy and is found in foods such as meat, poultry, and fish. Full definition
«In the Earth's deep mantle, we should find iron in its less oxidized form, known as ferrous iron, or in its metal form. (sciencedaily.com)
There is more elemental iron and bioavailability in ferrous iron than ferric iron.5 (integrativehealthcare.com)
The analysis shows that the soft tissue layer around the bones retained traces of ferrous iron, a relic left over from haemoglobin that was also trapped in the sample. (sciencedaily.com)