Monthly Archives: September 2020

Pentlandite – the most important nickel ore

Pentlandite

  • Named after the Irish natural historian, J. B. Pentland (1797-1873)
  • Pentlandite is the most important nickel ore
  • Formula: (Fe,Ni)9S8
  • Space group: Fm-3m (No. 225)
  • Crystal system: cubic
  • Crystal class: m-3m
  • Lattice parameters: a = b = c = 10.1075(1) Å, α = β = γ = 90°

Picture by: John Sobolewski (JSS) – http://www.mindat.org/photo-192760.html, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=9578696


Crystal structure (click on the picture to download the VESTA file):

(K. Momma and F. Izumi, “VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data,”J. Appl. Crystallogr., 44, 1272-1276 (2011).)

  • For both metal cation positions there is a complete disorder between Ni and Fe.
  • There are two distinct coordination environments; octahedrally coordinated metals at the center and all edge centers and tetrahedrally coordinated metals for the others.
  • Eight tetrahedra each form edge-connected Fe/Ni8(µ-S)6S8 motifs, that means cubes of metal ions with six face-capping and eight terminal S atom. If we take now these cubes and octahedra as building blocks they form a NaCl-like structure.
  • Fe/NiS4 tetrahedra (blue)
  • Fe/NiS6 octahedra (orange)
  • Fe (brown)
  • Ni (green)

For a 3D interactive version on sketchfab, see here:

https://skfb.ly/6UPTq

References:

[1] Tenailleau, C., Etschmann, B., Ibberson, R. M. & Pring, A.
A neutron powder diffraction study of Fe and Ni distributions in synthetic pentlandite and violarite using 60Ni isotope.
Am. Mineral. 91, 1442–1447 (2006)

[2] Stacey, T. E., Borg, C. K. H., Zavalij, P. J. & Rodriguez, E. E.
Magnetically stabilized Fe8(µ-S)6S8 clusters in Ba6Fe25S27.
Dalton Trans. 43, 14612–14624 (2014)