Tag Archives: mineral

Portlandite – basis for a very important building material

Portlandite

  • Named portlandite because it is a common product of hydration of portland cement
  • Formula: Ca(OH)2
  • Space group: P-3m1 (No. 164)
  • Crystal system: trigonal
  • Crystal class: -3 2/m
  • Lattice parameters: a = b = 3.5918 Å, c = 4.9063 Å, α = β = 90°, γ = 120°

Picture (public domain): SEM image of fractured hardened cement paste, showing plates of calcium hydroxide and needles of ettringite


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).)

  • CaO6 octahedra (blue)
  • Oxygen (red)
  • Hydrogen (white)

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

https://skfb.ly/6ItSG

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Strengite

Strengite

  • Named after Johann August Streng (1830-1897), German mineralogist, University of Giessen, Germany
  • Formula: FePO4 · 2 H2O
  • Space group: Pbca (No. 61)
  • Crystal system: orthorhombic
  • Crystal class: mmm
  • Lattice parameters: a = 8.722 Å, = 9.878 Å, c = 10.8117 Å, αβ = γ = 90°

Picture: Christian Rewitzer  | CC BY-SA-3.0


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).)

  • FeO6 octahedra (dark-red)
  • POtetrahedra (green-blue)
  • Oxygen (red)
  • Hydrogen (white)

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

https://skfb.ly/6BVJs

Celestial Celestine

Celestine

  • named from the Latin word caelestis meaning celestial, which in turn is derived from the Latin word caelum meaning sky or heaven because of its often soft blue color
  • pure Celestine is colourless
  • due to lattice defects in Celestine, colour centres are created which give the crystal its characteristic bluish colour
  • these centers are often additionally stabilized by the presence of pottasium ions
  • heating to over 200 °C “cures” these lattice defects and the mineral loses its color
  • radiation with X-rays creates new or more lattice defects and the color returns or can be intensified.
  • Formula: SrSO4
  • Space group: Pnma (No. 62)
  • Crystal system: orthorhombic
  • Crystal class: mmm
  • Lattice parameters:  a = 8.360 Å, b = 5.352 Å, c = 6.858 Å, αβγ = 90°

Picture: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0


Crystal structure (click on the pictures 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).)

  • SO4 tetrahedra (yellow)
  • SrO8 polyhedra (green)
  • Oxygen (red)

For a 3D interactive version, see here:

https://skfb.ly/6zG6R

Nadorite

Nadorite

  • Named after its type locality Djebel Nador, Constantine, Algeria
  • Formula: PbSbO2Cl
  • Space group: Cmcm (No. 63)
  • Crystal system: orthorhombic
  • Crystal class: mmm
  • Lattice parameters: a = 5.603 Å, b = 12.245 Å, c = 5.448 Å, α = β = γ = 90°

 

Picture: Christian Rewitzer – CC-BY-SA-3.0

 


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).)

 

 

  • PbO4Cl4 square antiprisms (gray)
  • SbO4 square pyramids (purple)
  • Oxygen (red)
  • Chlorine (green)

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

https://skfb.ly/6sErr

Ilmenite – the titanium dioxide source

Ilmenite

  • Named after it’s type locality, the Ilmensky Mountais in the Southern Urals (Russia)
  • Most important titanium mineral; it is predominantly mined for titanium dioxide production
  • Formula: FeTiO3
  • Space group: R-3 (No. 148)
  • Crystal system: trigonal
  • Crystal class: -3
  • Lattice parameters: a = b = 5.0884 Å, c = 14.0855 Å, αβ = 90°, γ = 120°

Picture by Modris Baum (Public Domain)


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).)

  • FeO6 distorted octahedra (brown)
  • TiO6 distorted octahedra (blue)
  • Oxygen (red)
  • The structure can be derived from the corundum (Al2O3) type: in corundum all cations are identical but in ilmenite Fe2+ and Ti4+ ions occupy alternating layers perpendicular to the c axis
  • Within the alternating layers the FeO6 / TiO6 octahedra are edge-connected to give six-membered rings (the centre of the hexagons are unoccupied)

For a 3D interactive version, see here:

https://skfb.ly/6ps9E