Magnetite
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Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to
Magnetite from Bolivia
Magnetite is one of the very few minerals that is ferrimagnetic; it is attracted by a magnet as shown here
Magnetite and other heavy minerals (dark) in quartz beach sand (Chennai, India)
Octahedral crystals of magnetite up to 1.8 cm across, on cream colored feldspar crystals, locality: Cerro Huañaquino, Potosí Department, Bolivia
Hematite
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Hematite, also spelled as haematite, is a common iron oxide compound with the formula Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is
Magnetite
…in the rounded crystals. Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce hematite, and the mineral pair forms a buffer that can control how oxidizing its environment is (the oxygen fugacity). This buffer is known as the hematite-magnetite…
Hematite crystals from Brazil
Crystal structure of hematite
Image mosaic from the Mars Exploration Rover Microscopic Imager shows hematite spherules partly embedded in rock at the Opportunity landing site. Image is around 5 cm (2 in) across.
A rare pseudo-scalenohedral crystal habit