These metals consist of ferrous metals and alloys. Zinc improves wetting of ferrous metals, indium as well. It works by converting the ferric iron in hemoglobin to ferrous iron. The teeth are coated with magnetite, a hard ferric/ferrous oxide mineral. Another method is electrolysis of ferrous chloride onto an iron cathode. A typical iron source is ferrous fumarate. The binary ferrous and ferric halides are well-known. Chromate conversion coatings can be applied over phosphate conversion coatings used on ferrous substrates. Titanium dioxide with ferrous oxide gives rise to ilmenite. Cold saws are capable of machining most ferrous and non-ferrous alloys. Lime is used extensively for wastewater treatment with ferrous sulfate. The Iron Age refers to the advent of iron working (ferrous metallurgy). In archaeology, the Iron Age refers to the advent of ferrous metallurgy. Prussian blue is produced by oxidation of ferrous ferrocyanide salts. Magnets from electronics are shown used to gather the smallest of ferrous metal scraps.