There are four main ores of iron that are found in the earth. These four types are: magnetite, hematite, limonite, and siderite. Iron is very essential for various industries; it is used for manufacturing steel, which is the backbone of many industries.
Let us look at the 4 main ores of iron and also compare their chemical composition and the percentage of iron present in them in the table below.
Ores of Iron: Chemical Composition and Iron Percentage Comparison
The following table shows the composition of the 4 main ores of iron: hematite, magnetite, limonite, and siderite.
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Ore
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Formula
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Theoretical Iron (Fe) Content
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Typical Ore-Grade Iron%
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Color
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Magnetite
|
Fe3O4
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72.4%
|
60-70%
|
Black, metallic
|
|
Hematite
|
Fe2O3
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69.9%
|
60-70%
|
Red to reddish-brown
|
|
Limonite
|
FeO(OH)·nH2O
|
60%
|
40-60%
|
Yellowish-brown
|
|
Siderite
|
FeCO3
|
48.2%
|
30-40%
|
Brown to grey
|
Magnetite has the highest concentration of iron at about 72.4% while hematite is the second best in terms of iron content with 69.9%. Magnetite and Hematite are oxide ores of Iron, while Limonite is a hydrated iron oxide-hydroxide, and siderite is a carbonate.
Siderite contains the lowest iron content among the 4 main ores of iron at 48%.
Did You Know
Although magnetite has the most iron content among all iron ores, the most mined ore is hematite, because it is easier to extract from ore and is more cost-effective than magnetite.
Let us learn more about the four main ores of iron below.
1. Magnetite
Source: A_Pobedimskiy/Getty Images
Magnetite is the iron ore with the highest iron content at 72.4%, it appears as black octahedral crystals and is strongly magnetic in nature. Although it has the highest iron content of any ore, yet low concentrations of ore are found in deposits, that means more rock needs to be mined in order to get good quality ore
2. Hematite
Source: Shutterstock
Hematite is the most abundant iron ore in the world, it is also the most mined ore primarily because of high iron content in the ore and the ease with which it can be extracted from the ore. It appears as steel gray, dark silver
3. Limonite
Source: Shutterstock
Limonite is a mixture of hydrate iron oxide and hydroxide appearing as an amorphous mass in various shades of yellow, orange and brown. It contains an iron content of 40-60%, making it a low grade iron ore as compared to magnetite and hematite.
4. Siderite
Source: Shutterstock
Siderite is a carbonate ore of iron, and one that has the lowest iron content among all ores of iron. At 30-40% iron content, it is the most inferior of all the iron ores. Hence, mining of such ore is not economically viable.
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