A single Magnetite Crystal, showing Octahedral Crystal shape. An interesting piece for metal or Aussie collectors, hard to come across for sale. The specimen is mounted on a perspex pad for enhanced display. We have added a small neo magnet which sticks well.
Yinnietharra, Western Australia.
1.9cm x 1.9cm x 1.7cm, 13g.
Magnetite is an important iron ore, along with hematite. Nanoinclusions of magnetite crystals cause the iridescence of Rainbow Obsidian (Nadin, 2007). Extremely thin layers of 200-nm octahedral crystals of magnetite give some basalt surfaces an iridescent sheen.
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.