Magnetite is an oxide of iron (as is hematite). It is not a component of ordinary rust, although it can form as iron oxidizes in a dry environment. When you see sparks from welding operations or from iron striking a hard surface (as when it is held against a spinning grinder), the sparks are due to the rapid (and exothermic) oxidation of tiny particles of iron into magnetite.

Magnetite is a natural magnet, hence the name, giving it a very nice distinguishing characteristic. Explaining the magnetism is not easy but here is a go at it. Remember, electricity produces magnetic fields just as magnetism produces electric fields. Magnetite is a member of the spinel group which has the standard formula A(B)2O4. The A and B represent usually different metal ions that occupy specific sites in the crystal structure. In the case of magnetite, Fe3O4, the A metal is Fe +2 and the B metal is Fe +3; two different metal ions in two specific sites. This arrangement causes a transfer of electrons between the different irons in a structured path or vector. This electric vector generates the magnetic field.

Magnetite is the primary oxide of iron found in meteorites (and thus presumably in asteroids).

Thermite is a mixture of powdered magnetite and powdered aluminum. When ignited, the aluminum fuel burns using the magnetite as an oxidizer, resulting in much heat, aluminum oxide (corundum), and molten iron.


  • Color is black.
  • Luster is metallic to dull.
  • Transparency: Crystals are opaque.
  • Crystal System is isometric; 4/m bar 3 2/m
  • Crystal Habits are typically octahedrons but rarely rhombododecahedron and other isometric forms, most commonly found massive or granular. Twinning of octahedrons into spinel law twins is seen occasionally.
  • Cleavage is absent although octahedral parting can be seen on some specimens.
  • Fracture is conchoidal.
  • Hardness is 5.5 - 6.5
  • Specific Gravity is 5.1+ (average for metallic minerals)
  • Streak is black.
  • Associated Minerals are talc and chlorite (schists), pyrite and hematite.
  • Other Characteristics: Magnetism stronger in massive examples than in crystals, striations on crystal faces (not always seen).
  • Notable Occurrences include South Africa, Germany, Russia and many localities in the USA.
  • Best Field Indicators are magnetism, crystal habit and streak.
This Site Awarded
Available MAGNETITE specimens:
MAGNETITE specimen MAG-29
$ 28.00 -60% = $ 11.20
Dims: 1.04x1.03x0.94in (2.64x2.61x2.38cm) .... Wt: 0.99oz (28.0g) .... Loc: Kashkanar, Chelyabinsk Oblast, Russia
This magnetite specimen displays a number of crystals, most of which show some damage. It is mounted in a plastic thumbnail specimen box.
no photo
$ 11.20
no photo
see this List of ALL specimens including SOLD ones


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