What Type of Rock Is Hematite?
According to geology.com, hematite is the most common form of iron ore or iron oxide, which is classified as a chemical sedimentary rock form. The chemical expression for hematite is Fe2O3. Both the kidney ore form and the crystalline form of hematite are rare and eagerly sought by collectors. An old superstition surrounding the stone is that it forms for the bloodshed of battles wages on land.
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Chemical Sedimentary Rock
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Chemical sedimentary rocks such as hematite are formed through a process that involves the combination of chemicals in a solution that are then deposited. In the case of hematite, the chemicals involved in the combination include mainly iron and oxygen, but can also contain other solutions.
Formation
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When formed, hematite is expressed in two formations: metallic hexagonal crystals and granulated concretions or clusters of sediment. Another type of hematite, known for its flower-like appearance, is rose hematite, which is formed with bladed crystals that cluster in a circular pattern. Tyger ore is a form of ore dating back 2.2 billion years, and consists of layers of jasper, chert or tiger's eye quartz with hematite. Kidney ore is another form that presents itself in lumpy kidney-shaped clusters of sediment. Oolitic hematite is a reddish-brown formation of the stone that is made up of small grains and appears to have an earthy sheen. A more ornamental form of hematite is called specularite; this stone is flaky and has a shiny silver-gray tone to it.
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Appearance
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Hematite that has lots of inclusions from the earth appears as a red or reddish-brown rock, while more pure forms appear to be silver, gray or black. Parts of the rock appear smooth and metallic, while other parts appear rough and grainy. When in powder form, the stone has a blood-red hue, which is how it got its Grecian name.
Hardness
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On Moh's Hardness Scale, which measures the relative strength of rocks, hematite ranks at a hardness of 5.5 to 7 on a scale of 0-10.
Uses
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The iron ore hematite is the most important source of mined iron, and it is also used to create paint pigments and in solutions used for polishing.
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References
- Photo Credit mineral image by Marek Kosmal from Fotolia.com
