What is magnetite and what are its uses?

A geological site provides that “Magnetite is a very common iron oxide (Fe3O4) mineral that is found in igneous, metamorphic, and sedimentary rocks. It is the most commonly mined ore of iron being the mineral with the highest iron content (72.4%). Magnetite is very easy to identify. It is one of the few minerals that are attracted to a common magnet.”  The uses include: as an ingredient in an abrasive mix known as ‘emery’, and includes waterjet cutting; “… as a toner in electrophotography, as a micronutrient in fertilizers, as a pigment in paints, and as an aggregate in high-density concrete”; once the rock is powdered and shaped into pellets, they are loaded into a blast furnace at a mill to produce iron or steel.


A science reference site explains: “Magnetite increases the density of most mixtures in which it is present. This property allows magnetite to be used in the manufacture of heavy concrete, water filtration, coal mining, landscaping and production of certain iron-based chemicals.

When magnetite is added to a concrete mix, it produces heavy concrete, which is twice as dense as standard concrete. Heavy concrete is widely used in buildings that require protection from radiation, such as nuclear power plants, X-ray facilities and uranium mining sites. Heavy concrete retains heat more efficiently than standard concrete and can be used in building houses to retain solar heat.

Magnetite can also be used in water filtration systems. A water filtration system with magnetite has a more aggressive backwash in the cleaning phase, as well as the ability to recover the magnetite by using a magnet.

It is also used in coal mining operations as a slurry with water to remove the heavier impurities by allowing the less dense coal to float to the surface. The magnetite can be reused in this process 90 percent of the time.

Magnetite is also used as a source of iron to manufacture iron-based chemicals and fertilizers. Ferric chloride and ferric sulphate are manufactured with magnetite as one of the starting materials. These chemicals are effective in clarifying raw water in water purification plants. The dark, glossy nature of magnetite ore has led to its use in landscaping as accent rocks.”

Without doubt Magnetite has value for our industrial and city based society. I can understand why those who discovered this mineral at Savage River were excited.  The history of its discovery in 1887, then development from the mid-1960s can be read here.

I accept, with sadness but understanding, that pristine old growth rare forests cannot exist at the same time and place as mineral ores deemed essential for manufactured resources; a part of the Tarkine wilderness has not been able to continue to exist because of the extraction of magnetite.  For those who might say, ’well dig magnetite from elsewhere’, I say ‘there will always be native vegetation and/or fauna that depends on any landscape for its continued existence so digging up minerals will always create habitat problems’. Who among us, who love the natural untouched landscape, would give up the perceived benefits which come from removing mineral ores from the ground?  Would you?

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