Despujolsite

Despujolsite

  • Named in honor of Pierre Despujols (1888–1981), the founder of the Moroccan Geologic Survey (“Service de la carte géologique du Maroc”)
  • The mineral was first observed in 1962 in manganese ore samples from Tachgagalt (Anti-Atlas, Morocco).
  • Formula: Ca3Mn(SO4)2(OH)6  · 3 H2O
  • Space group: P-62c
  • Crystal system: hexagonal
  • Crystal class: -6m2
  • Lattice parameters: a = b =  8.5405(5) Å, c = 10.8094(9) Å, α = β = 90°, γ  120°
Despujolsite_0438792001298611550

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).)

Despujolsite
  • CaO8 polyhedra (blue)
  • Mn(OH)6 octahedra (purple)
  • SO4 tetrahedra (yellow)
  • Oxygen (red)
  • Hydrogen (white)

For a 3D interactive version, see here:

https://skfb.ly/onvGo

Refs:

[1] M.C. Barkley, H. Yang, S.H. Evans, R.T. Downs, M.J. Origlieri, Acta Cryst E 2011, 67, i47-i48.
DOI: 10.1107/S1600536811030911

Space Group Diagrams (not only) for Lecturers

I’ve started another ‘230 project’.

This time it is concerned with space group diagrams.

Of course, the No. 1 source for such diagrams, i.e. symmetry element and general position diagrams, is Volume A of the International Tables for Crystallography (ITA). As valuable as they are for the daily life of a crystallographer, they are unsuitable when it comes to teaching.

Hitherto, there is another extremely valuable online resource for these diagrams:

The Hypertext Book of Crystallographic Space Group Diagrams and Tables

However, one of the features I don’t like about these diagrams is that they decided to present both diagrams (symmetry elements and general positions) in a superimposed fashion.

For this reason I decided to draw all diagrams again and to make them publicly available (CC license) in various formats (as a PNG picture, a PDF, and a PPT file) – ready for use for teaching purposes.

However, there will be limitations. Different origin choices will be taken into account, but further different settings will be disregarded. And I do not know, if I will be able to manage the drawings of all diagrams for the cubic space groups. Lets see 🙂

Up to now, the first two space groups of the triclinic crystal system are ready. Until the end of the month the diagrams for all monoclinic space groups should be available. Then further diagrams will be added from time to time.

Have fun!

Kapellasite

Kapellasite

  • Named after Christo Kapellas (1938-2004), collector and mineral dealer of Kamariza, Lavrion, Greece
  • Kapellasite is isostructural with Haydeeite [Cu3Mg(OH)6Cl2]
  • Kapellasite is a metastable polymorph of Herbertsmithite
  • Formula: Cu3Zn(OH)6Cl2
  • Space group: P-3m1 (No. 164)
  • Crystal system: trigonal
  • Crystal class: -3m
  • Lattice parameters: a = b = 6.300(1) Å, c =  5.733(1) Å, α = β = 90°, γ = 120°

Crystal structure[1] (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).)

  • CuO4 square-planar coordination polygons (blue)
  • ZnO6 distorted octahedra (gray)
  • Oxygen (red)
  • Chlorine (green)

For a 3D interactive version, see here:

https://skfb.ly/6ZNHM

References:

[1] W. Krause, H.-J. Bernhardt, R.S.W. Braithwaite, U. Kolitsch, R. Pritchard
Kapellasite, Cu3Zn(OH)6Cl2, a new mineral from Lavrion, Greece, and its crystal structure
Mineralogical Magazine, 2006, 70, 329-340
DOI: 10.1180/0026461067030336

Bloedite

Blödite (also Bloedite)

  • named after the German mineralogist and chemist Karl August Blöde (1773 – 1820)
  • fun fact: the German adjective “blöd(e)” means “stupid”
  • Formula: Na2Mg(SO4)2  · 4 H2O
  • Space group: P21/a
  • Crystal system: monoclinic
  • Crystal class: 2/m
  • Lattice parameters: a = 11.126(2), b =  8.242(1) Å, c = 5.539(1) Å, α = 90°, β = 100.84(1)°, γ  90°

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)
  • (distorted) NaO6 octahedra (purple)
  • MgO6 octahedra (green)
  • Oxygen (red)
  • Hydrogen (white)

For a 3D interactive version, see here:

https://skfb.ly/6ZEPS

Refs:

[1] F. C. Hawthorne, The Canadian Mineralogist 1985, 23, 669-674.
(PDF)

Ice VI

Phase diagram of water
  • Can be formed from liquid water at 11 kbar by lowering the temperature to approx. -3 °C
  • Density: 1.31 g/cm3

Structural features

Crystal structure of Ice VI
  • Ice VI is a proton-disordered phase
  • it is composed of two independent interpenetrating networks of H-bonded water molecules (shown above in blue and red, respectively)
  • the main structural motif is a tricyclic, cage-like water hexamer, similar as in liquid water
A tricyclic water hexamer composed of four-membered rings
  • This motif is also found for the silicon atoms in the zeolite edingtonite, see here for comparison.
  • The respective topology of the underlying net is edi, a binodal (4,4)-c net with transitivity pqrs = 2343
  • Space group: P42/nmc (No. 137)
  • Crystal system: Tetragonal
  • Lattice parameters:
    • a = b = 6.116(1) Å, c = 5.689(1) Å
    • α = β = γ = 90°

Literature:

[1] W. F. Kuhs, J. L. Finney, C. Vettier and D. V. Bliss, Structure and hydrogen ordering in ices VI, VII and VIII by neutron powder diffraction. J. Chem. Phys. 1984, 81, 3612-3623.
DOI: 10.1063/1.448109

Here, you can download the CIF.

Atomistic structure figures were created with:

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

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)

Textbook available

I’m very happy that the English edition of my book on #crystallography is finally available!

I know it is a bit expensive, but at least you get the eBook when you order the hardcover version.

You can order it here:

https://www.springer.com/us/book/9783030351090

On this page you can find some electronic supplementary materials, for instance CIF files of the crystal structures that are mentioned in the book, sheets for paper models of typical crystal shapes and some animations.

Atacamite and Hibbingite

Atacamite

  • Named after its type locality, the Atacama desert in Chile.
  • Atacamite is isostructural with Hibbingite [Fe2Cl(OH)3], and Kempite [Mn2Cl(OH)3]
  • In 2002 it was found out that the jaws of the marine bloodworm Glycera dibranchiata contain Atacamite.[1]
  • Atacamite is polymorphous with Botallackite and Clinoatacamite (both monoclinic).
  • Formula: Cu2Cl(OH)3
  • Space group: Pnma (No. 62)
  • Crystal system: orthorhombic
  • Crystal class: mmm
  • Lattice parameters: a = 6.030(2) Å, b =  6.865(2) Å, c = 9.120(2) Å, α = βγ = 90°

Picture: By Stefan Schorn – CC BY-SA 3.0
http://www.mineralienatlas.de/lexikon/index.php/Bildanzeige?pict=1081079762,
https://commons.wikimedia.org/w/index.php?curid=399210


Crystal structure[2] (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).)

  • CuO5Cl distorted octahedra (orange)
  • CuO4Cl2 distorted octahedra (blue)
  • Oxygen (red)
  • Chlorine (green)
  • Hydrogen (white)

For a 3D interactive version, see here:

https://skfb.ly/6QpQY

References:

[1] H.C. Lichtenegger, Th. Schöberl, M.H. Bartl, H. Waite, G.D. Stucky
Science 2002, 298, 389-392.
DOI: 10.1126/science.1075433

[2] J.B. Parise, B.G. Hyde
Acta Cryst. C 1986, 42, 1277-1280.
DOI: 10.1107/S0108270186092570


Hibbingite

  • Named after its type locality, the city of Hibbing, which was built on the rich iron ore of the Mesabi Iron Range. At the edge of the town is the largest open-pit iron mine in the world.
  • Hibbingite is isostructural with Atacamite [Cu2Cl(OH)3] and Kempite [Mn2Cl(OH)3]
  • Formula: Fe2Cl(OH)3
  • Space group: Pnma (No. 62)
  • Crystal system: orthorhombic
  • Crystal class: mmm
  • Lattice parameters: a = 6.3373(2) Å, b =  6.9892(2) Å, c = 9.3457(3) Å, α = βγ = 90°

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).)

  • FeO5Cl distorted octahedra (green)
  • FeO4Cl2 distorted octahedra (brown)
  • Oxygen (red)
  • Chlorine (green)
  • Hydrogen (white)

For a 3D interactive version, see here:

https://skfb.ly/6QpRS

Reference:

N.V. Zubkova, I.V. Pekov, E.V. Sereda, V.O. Yapaskurt, D.Y. Pushcharovsky
Z. Kristallogr. 2019, 234 (6), 379-382.
DOI: 10.1515/zkri-2018-2124


 

Schoenfliesite

Schoenfliesite

  • Named in 1971 by George T. Faust and Waldemar T. Schaller in honor of Arthur Moritz Schoenflies ( 17 April 1853 – 27 May 1928) Professor of Mathematics, University of Frankfurt. Schoenflies’ researches in group theory and topology resulted in his proof of the 230 space groups.
  • Formula: MgSn(OH)
  • Space group: Pn-3 (No. 201)
  • Crystal system: cubic
  • Crystal class: m-3
  • Lattice parameters: a = b = c = 7.7449(4) Å, α = β = γ = 90°

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).)

  • MgO6 octahedra (orange)
  • SnO6 octahedra (blue-gray)
  • Hydrogen (white)

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

https://skfb.ly/6QpyS

Reference:

Description of Schoenfliesite, MgSn(OH)6, and Roxbyite, Cu1.72S, from a 1375 BC Shipwreck, and Rietveld Neutron-diffraction Refinement of Synthetic Schoenfliesite, Wickmanite, MnSn(OH)6, and Burtite, CaSn(OH)6
L.C. Basciano, R.C. Peterson, P.L. Roeder
The Canadian Mineralogist 1998, 36, 1203-1210.

Spangolite – A Pyroelectric Copper Sulfate Sheet Mineral

Spangolite

  • Named in honour of Norman Spang (1841–1922), a mineral collector from Pennsylvania, USA; for details, see here.
  • Spangolite is pyroelectric
  • Formula: Cu6Al(SO4)(OH)12Cl · 3 H2O
  • Space group: P31(No. 159)
  • Crystal system: trigonal
  • Crystal class: 3m
  • Lattice parameters: a = b = 8.254(4) Å, c = 14.354(8) Å, α = β = 90°, γ = 120°

Picture: Christian Rewitzer, CC BY-SA 3.0
https://commons.wikimedia.org/w/index.php?curid=14865917


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).)

  • CuO6 distorted octahedra (blue)
  • AlO6 octahedra (orange)
  • SOtetrahedra (yellow)
  • Oxygen (red)
  • Chlorine (green)
  • Hydrogen (white)

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

https://skfb.ly/6Q6U7

References:

[1] Spangolite
H. A. Miers
Mineralogical Magazine 1894, 10, 273-277

DOI: 10.1180/minmag.1894.010.48.02

[2] The Crystal Structure of Spangolite, a Complex Copper Sulfate Sheet Mineral
F.C. Hawthorne, M. Kimata, R.K. Eby
American Mineralogist 1993, 78 (5-6), 649-652.