Minerals with Iron – Which Minerals Have the Most
So you are wondering what minerals have iron in them. You might be surprised to know that only a few minerals have a good amount of iron in them. Lucky for us, iron contained in these few minerals are quite abundant on our earth, as iron has proven to be quite useful.
Retrieving iron in minerals has been around for thousands of years. In that time frame, it has been found that minerals with larger quantities of iron include pyrite, magnetite, chalcopyrite, hematite, goethite, limonite, greenalite, and siderite.
The minerals with the highest iron content will be magnetite, hematite, goethite, and limonite. These minerals range in about 60% to 70%+ in iron content. Magnetite is the most widespread mineral on earth with roughly the highest iron content.
| Minerals with Iron | Percentage of Iron (Approx.) | Chemical Formula |
| Magnetite | ~72% | Fe2+Fe3+2O4 |
| Hematite | ~69% | Fe2O3 |
| Limonite | ~60% | FeO(OH)·nH2O |
| Siderite | ~48% | FeCO3 |
| Pyrite | ~46% | FeS2 |
| Chalcopyrite | ~30% | CuFeS2 |
| Goethite | ~63% | FeO(OH) |
| Greenalite | ~44% | (Fe2+,Fe3+)2-3Si2O5OH4 |
Extraction from Iron Ore
Iron ore, or iron rock, is the host rock in which iron rich minerals can be extracted. The most commonly extracted minerals within iron ore are magnetite, hematite, goethite, and siderite. Iron is most commonly extracted from the iron rock by way of blast furnace at very high temperatures.
Iron ores can contain oxide and other impurities. When the ore is heated, it will separate the oxygen from the iron. Additionally, adding some calcium oxide will help remove the impurities, often called slag, from the iron.
The iron industry has found that magnetite, hematite, goethite, and siderite are the best sources for extracting iron for a good reason. These minerals contain fewer impurities such as sulfur or phosphorus, which can make iron brittle and difficult to work with.
The most common types of high grade iron ore mined for its iron will be massive hematite, magnetite, titanomagnetite, and pisolitic ironstone. These iron ores can contain minerals high in iron content as well as minerals that have cleaner, or more pure iron.
Rocks with the Most Iron
The most common kind of rock that contains minerals with iron are sedimentary rocks. For a rock to be considered iron rich, it must contain 15% or more iron in its composition to qualify. Some great examples of potential iron rich sedimentary rocks are sandstone, black shale, and dolomite.
A good way to tell if a rock has iron in it will be by seeing a metallic color or luster within the rock. For rocks like quartz rich sandstone, you can see red, brown, and even yellow banding. This banding is the indication of iron within the host rock.
Color does play an important part in identifying types of iron. Ferrous iron, iron (II) will have a green color. Ferric iron, iron(III) will often have colors that are reddish or brownish.
How Hard are Minerals with Iron
Iron has a hardness of 4 on the Mohs scale of hardness. Though the Mohs scale of hardness is typically used for minerals, often metals like iron are compared. Iron is compared to the same hardness as the mineral fluorite.
Chemical bonds in minerals containing iron can be stronger than just the extracted iron itself. Hematite and magnetite are great examples of that both coming in at about 5.5 to 6.5 on the Mohs scale of hardness.
With refinement and processing iron can be purified and also combined with other metals. Steel can be slightly harder than iron as it is processed and impurities are removed. Hardened steel can fall at around an 8 on the Mohs scale of hardness.
Places where there are Minerals with Iron
Minerals with iron are found all over the world. Larger iron mineral deposits can be found in Australia, Brazil, China, India, Russia, and the USA. As these countries have an abundance of iron, you might expect that they may also produce the most.
The most mined and biggest exporter of Iron ore in 2019 was Australia. As time goes on that may change, though currently Brazil, China, India, Russia, and USA are all very distant in production comparatively. See “List of countries by iron ore production”. (Wikipedia reference for Iron ore production by country)
