Tag Archives: minerals

Mellite

Mellite

  • Also known as honeystone due to its often honey-yellow color
  • Mellite is the aluminium salt of mellitic acid, i.e. benzene hexacarboxylic acid
  • Formula: Al2C6(COO)6 · 16 H2O
  • Space group: I41/acd (No. 142)
  • Crystal system: tetragonal
  • Crystal class: 4/mmm
  • Lattice parameters: a = b = 15.553 Å, c = 23.110 Å, α = β = γ = 90°

Picture: Rob Lavinsky, iRocks.com – 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).)

 

 

  • AlO6 octahedra (blue)
  • Oxygen (red)
  • Carbon (black)
  • Hydrogen (white)

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

https://skfb.ly/6rSSR

 

Lavendulan

Lavendulan

  • The colour varies between turquoise and lavender, often also electric blue specimens can be found (see the picture below)
  • Formula: NaCaCu5(AsO4)4Cl · 5 H2O
  • Space group: P21/n (No. 14)
  • Crystal system: monoclinic
  • Crystal class: 2/m
  • Lattice parameters: a =  10.011, b = 19.478 Å, c = 10.056 Å, α = 90° β = 90.37°, γ = 90°

Picture: CC BY-SA 3.0 | Christian Rewitzer


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).)

  • CuO5 and CuO4Cl tetragonal pyramids (blue)
  • CaO7 polyhedra (light blue)
  • NaO6 distorted trigonal prismatic units (yellow)
  • AsO4 tetrahedra (green)
  • Chlorine (bright green)
  • Oxygen (red)
  • Oxygen of water molecules (dark red)

For a 3D interactive version, see here:

https://skfb.ly/6qsoV

Keyite – A Complex Copper-Zinc-Cadmium Arsenate

Keyite

  • Named after the mineral dealer Charley Key, who discovered some tiny blue crystals of this mineral on a sample of green Adamite
  • Formula: Cu3(Zn,Cd)4Cd2(AsO4)6· 2 H2O
  • Space group: I2/a (No. 15)
  • Crystal system: monoclinic
  • Crystal class: 2/m
  • Lattice parameters: a = 11.654 Å, b = 12.780 Å, c = 6.268 Å, αγ = 90°, β = 99.11°

Picture: CC BY-SA 3.0 | Christian Rewitzer


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).)

  • CuO4 square-planar units (blue)
  • CuO6 distorted octahedra (blue)
  • CdO6 distorted trigonal prismatic units (pink)
  • AsO4 distorted tetrahedra (green)
  • Oxygen (red)
  • Oxygen of water molecules (black(

For a 3D interactive version, see here:

https://skfb.ly/67tQD

Jarosite – Indicator of (liquid) water on Mars

Jarosite

  • Named after its type locality, Barranco del Jaroso in the Sierra Almagrera (near Los Lobos, Cuevas del Almanzora, Almería, Spain)
  • In 2004 the Mars Exploration Rover – B found Jarosite on Mars. Because on Earth Jarosite is only formed in liquid water, this finding strongly indicates that Mars once possessed large amounts of liquid water.
  • Formula: KFe3(OH)6(SO4)2
  • Space group: R-3m (No. 166)
  • Crystal system: trigonal
  • Crystal class: -3m
  • Lattice parameters: a = b = 7.304 Å, c = 17.268 Å, αβ = 90°, γ = 120°

Picture: CC BY-SA 3.0 | Christian Rewitzer


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).)

  • KO12 only very slightly distorted icosahedra (purple)
  • FeO6 octahedra (blue)
  • SO4 tetrahedra (yellow)
  • Oxygen (red)

For a 3D interactive version, see here:

https://skfb.ly/6pGuY

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

Hercynite – A ferro spinel

Hercynite

  • Named after the latin name Silva Hercynia of the Bohemian Forest, where this mineral was first found
  • it is a ferro spinel
  • Formula: FeAl2O4
  • Space group: Fd-3m (No. 227)
  • Crystal system: cubic
  • Crystal class: m-3m
  • Lattice parameters: a = b = c = 8.1458 Å, α = β =  γ = 90°

Picture: CC BY-SA 3.0 nl | Fred Kruijen | http://www.mindat.org/photo-73060.html

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).)

  • FeO4 tetrahedra (orange)
  • Al (blue), octahedral oxide coordination environment
  • Oxygen (red)

For a 3D interactive version, see here:

https://skfb.ly/66QEE

Gottlobite: The “Thank God” Mineral

Gottlobite

  • Literally translated from German the meaning is “Thank God”; it is named after its type locality, the hill Gottlob (573 m) near Friedrichroda, Thuringia, Germany
  • Known only since 1996
  • Formula: CaMg(VO4,AsO4)(OH)
  • Space group: P212121 (No. 19)
  • Crystal system: orthorhombic
  • Crystal class: 222
  • Lattice parameters: a = 7.501 Å, b = 9.010 Å, c = 5.941 Å, α = β =  γ = 90°

gottlobite

Picture: CC BY-SA 3.0 de – Thomas Witzkehttp://tw.strahlen.org/typloc/gottlobit.html


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).)

gottlobite

View along the c axis.

  • MgO6 octahedra (orange)
  • AsO4/VO4 tetrahedra (purple)
  • Ca (blue)
  • Oxygen (red)

For a 3D interactive version, see here:

https://skfb.ly/6nBSF