Magnetite

In addition to igneous rocks, magnetite also occurs in sedimentary rocks, including banded iron formations and in lake and marine sediments as both detrital grains and as magnetofossils. Magnetite nanoparticles are also thought to form in soils, where they probably oxidize rapidly to maghemite.

Biomagnetism is usually related to the presence of biogenic crystals of magnetite, which occur widely in organisms. These organisms range from bacteria (e.g., Magnetospirillum magnetotacticum) to animals, including humans, where magnetite crystals (and other magnetically-sensitive compounds) are found in different organs, depending on the species. Biomagnetites account for the effects of weak magnetic fields on biological systems. There is also a chemical basis for cellular sensitivity to electric and magnetic fields (galvanotaxis). Pure magnetite particles are biomineralized in magnetosomes, which are produced by several species of magnetotactic bacteria. Magnetosomes consist of long chains of oriented magnetite particle that are used by bacteria for navigation. After the death of these bacteria, the magnetite particles in magnetosomes may be preserved in sediments as magnetofossils. Some types of anaerobic bacteria that are not magnetotactic can also create magnetite in oxygen free sediments by reducing amorphic ferric oxide to magnetite. Several species of birds are known to incorporate magnetite crystals in the upper beak for magnetoreception, which (in conjunction with cryptochromes in the retina) gives them the ability to sense the direction, polarity, and magnitude of the ambient magnetic field. Chitons, a type of mollusk, have a tongue-like structure known as a radula, covered with magnetite-coated teeth, or denticles. The hardness of the magnetite helps in breaking down food, and its magnetic properties may additionally aid in navigation. Biological magnetite may store information about the magnetic fields the organism was exposed to, potentially allowing scientists to learn about the migration of the organism or about changes in the Earth's magnetic field over time.

The chemical composition of magnetite is FeFe2O4. The main details of its structure were established in 1915. It was one of the first crystal structures to be obtained using X-ray diffraction. The structure is inverse spinel, with O ions forming a face-centered cubic lattice and iron cations occupying interstitial sites. Half of the Fe cations occupy tetrahedral sites while the other half, along with Fe cations, occupy octahedral sites. The unit cell consists of 32 O ions and unit cell length is a = 0.839 nm. Magnetite contains both ferrous and ferric iron, requiring environments containing intermediate levels of oxygen availability to form. Magnetite differs from most other iron oxides in that it contains both divalent and trivalent iron. As a member of the spinel group, magnetite can form solid solutions with similarly structured minerals, including ulvospinel (Fe2TiO4), hercynite (FeAl2O4) and chromite (FeCr2O4). Titanomagnetite, also known as titaniferous magnetite, is a solid solution between magnetite and ulvospinel that crystallizes in many mafic igneous rocks. Titanomagnetite may undergo oxyexsolution during cooling, resulting in ingrowths of magnetite and ilmenite.

Magnetite is a principal and important iron ore. As the name suggests, it is also magnetic and can sometimes be used as a magnet in its naturally-occurring form. These pieces are called lodestone. It is commonly reduced to pig iron to be made into steel, and is also used in magnetic recording and some coal mining processes.

Magnetite is part of ancient Greek myth that relates the story of a Greek shepherd in today's southern Turkey who came across some mysterious black stones. The iron tip of his staff was oddly drawn to these stones. They were made of magnetite, and had a magnetic attraction to the iron.

Magnetite is sometimes found in large quantities in beach sand. Such black sands (mineral sands or iron sands) are found in various places, such as Lung Kwu Tan of Hong Kong; California, United States; and the west coast of the North Island of New Zealand. The magnetite, eroded from rocks, is carried to the beach by rivers and concentrated by wave action and currents. Huge deposits have been found in banded iron formations. These sedimentary rocks have been used to infer changes in the oxygen content of the atmosphere of the Earth. Large deposits of magnetite are also found in the Atacama region of Chile; the Valentines region of Uruguay; Kiruna, Sweden; the Pilbara, Midwest and Northern Goldfields regions in Western Australia; the Eyre Peninsula in South Australia; the Tallawang Region of New South Wales; and in the Adirondack region of New York in the United States. Kediet ej Jill, the highest mountain of Mauritania, is made entirely of the mineral. Deposits are also found in Norway, Germany, Italy, Switzerland, South Africa, India, Indonesia, Mexico, Hong Kong, and in Oregon, New Jersey, Pennsylvania, North Carolina, West Virginia, Virginia, New Mexico, Utah, and Colorado in the United States. In 2005, an exploration company, Cardero Resources, discovered a vast deposit of magnetite-bearing sand dunes in Peru. The dune field covers 250 square kilometers (100 sq mi), with the highest dune at over 2,000 meters (6,560 ft) above the desert floor. The sand contains 10% magnetite. In large enough quantities magnetite can affect compass navigation. In Tasmania there are many areas with highly magnetized rocks that can greatly influence compasses. Extra steps and repeated observations are required when using a compass in Tasmania to keep navigation problems to the minimum. Magnetite crystals with a cubic habit have been found in just one location: Balmat, St. Lawrence County, New York. Magnetite can also be found in fossils due to biomineralization and are referred to as magnetofossils. There are also instances of magnetite with origins in space coming from meteorites.

Magnetite is a powerful stone that believers use to help a person attract the things, people, and situations they most desire for their life. Often referred to as lodestone, it has natural magnetic properties. When placed on the Crown and Root chakras it will align all of the chakras and bring a sense of balance throughout the body. Wear it daily for psychic protection and increased mental clarity.