Hexaferrum is a (formula: Fe, Os, Ru, Ir) hexagonal-dihexagonal dipyramidal yellowish steel-gray mineral containing iridium, iron, osmium, and ruthenium. It was named for the crystal morphology, being in the HEXAgonal system, and its composition, containing essential iron (Latin = FERRUM).

General information:

  • Formula: (Fe, Os, Ru, Ir)
  • Colour: steel-gray with the yellow tint
  • Luster: Metallic
  • Specific Gravity: 10.69 (Calculated)
  • Crystal System: Hexagonal.

Fig: Hexaferrum


  • Transparency: Opaque
  • Colour: steel-gray with the yellow tint
  • Hardness: 6 – 7 on the Mohs scale
  • Density: 10.69 g/cm3 (Calculated)

The deformation of the NaCl lattice, as measured by x-ray diffraction (XRD), served as a pressure indicator. At a pressure of 130 kbar (13 GPa) and room temperature, the body-centered cubic (BCC) ferrite powder transformed to the HCP phase. When the pressure was lowered, ε-Fe transformed back to ferrite (α-Fe) rapidly. A specific volume change of −0.20 cm3/mole ± 0.03 was measured. Hexaferrum, much like austenite, is denser than ferrite at the phase boundary. A shock wave experiment confirmed the diamond anvil results. Epsilon was chosen for the new phase to correspond with the HCP form of cobalt.

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.


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