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Appearance, Uses and History
Magnetite is one of the most important ores of Iron still used today – a banded sedimentary rock called taconite, a mixture of magnetite, hematite, and chert.
Magnetite is sometimes found in beach sand, in large quantities, where it is known as black sand.
Magnetite is extremely magnetic, attracted to a magnet. However, it is not a naturally occurring magnet. In certain areas, magnetite can affect navigation with a compass.
Lodestone is a naturally magnetic form of Magnetite, which acts as a magnet and does attract tiny particles of Iron. It is theorised that Lodestone is caused by lightning strikes to pieces of ground with high magnetite content near to the surface.
Magnetite forms part of the natural abrasive known as emery (a mixture of magnetite and corundum), although use of the natural emery has been superseded by a synthetic emery made by combining magnetite and aluminium oxide particles.
As an igneous rock forms, tiny crystals of magnetite may form inside. Due to their magnetism, they align themselves with the Earths magnetic field, which preserves the orientation of the Earths magnetic field at the moment of crystallisation. This means geologists are able to study the crystals and learn more about any changes to the magnetic field.
Magnetite is found worldwide, with significant deposits in numerous countries, most of which is not of any interest to mineral collectors due to its ‘massive’ nature.
Black sands can be found in Hong Kong, California, India, and New Zealand.
Large deposits of Magnesite can be found in Australia, Chile, Uruguay, Sweden, the USA, Mauritania, Romania, Norway, Ukraine and Peru.
For collectors, popular locales include
- Valais in Switzerland
- Nordmark in Sweden
- Kola in Russia
- Parachinar in Pakistan
- Potosi in Bolivia
- Several states of the USA, including Vermont, New York, New Jersey, and Pennsylvania.
Photos of Magnetite and Lodestone
Hazards and Warnings
Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.
When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.
- Fer oxydé magnétique
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