Iron is present in the earth’s crust in many types of minerals. The iron oxide minerals are hematite (Fe2O3) and magnetite (Fe3O4). What is the oxidation state of iron in each mineral? The iron ions in magnetite are a mixture of Fe2+ and Fe3+ ions. What is the ratio of Fe3+ to Fe2+ ions in magnetite? The formula for magnetite is usually written as FeO • Fe2O3. Does this make sense? Explain.