Afwillite – a calcium nesosilicate

Afwillite

• Named after the abbreviated discoverer Alpheus Fuller Williams (1874–1953), CEO of De Beers Consolidated Mines at that time
• Formula: Ca₃(SiO₃OH)₂ · 2 H₂O
• It belongs to the nesosilicates, i.e. there are only isolated SiO₄ tetrahedra
• Space group: Cc (No. 9)
• Crystal system: monoclinic
• Crystal class: m
• Lattice parameters: a = 16.278 Å, b = 5.6321 Å, c = 13.236, α =  γ = 90°, β = 134.898°

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Picture: Matteo Chinellato – http://www.mindat.org/photo-356015.html | CC BY-SA 3.0

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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).)

• Oxygen (red)
• Hydrogen (white)
• SiO₄ tetrahedra (yellow)
• CaO₇ polyhedra (light blue)

For a 3D interactive version, see here:

https://skfb.ly/6J7oy

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Stibnite – a black make-up mineral

Stibnite

• Synonym: Antimonite
• The mineral has been known since ancient times and was used as a paste with fat as black make-up powder to color eyelids and eyebrows. In Arabic culture, dark eye rims are regarded as the ideal of beauty and at the same time as a magical repellent.
• Formula: Sb₂S₃
• Space group: Pnma (No. 62)
• Crystal system: orthorhombic
• Crystal class: mmm
• Lattice parameters: a = 11.3107 Å, b = 3.8363 Å, c = 11.2285 Å, α = β = γ = 90°

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Picture: DerHexer, Wikimedia Commons, CC BY-SA 4.0

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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).)

• SbS₅ tetragonal pyramids (purple)

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

https://skfb.ly/6JoCM

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Valentinite

• named in honour of Basilius Valentinus, a writer on alchemy. He is the supposed author of the first book to give a detailed description of antimony and its compounds.
• Formula: Sb₂O₃
• Space group: Pccn (No. 56)
• Crystal system: orthorhombic
• Crystal class: mmm
• Lattice parameters: a = 4.89960 Å, b = 12.4490 Å, c = 5.41030 Å, α = β = γ = 90°

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Picture: Christian Rewitzer | CC BY-SA-3.0

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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).)

• corner-connected SbO₃ pyramids (purple)
• Oxygen (red)

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

https://skfb.ly/6utNI

Thaumasite – a suprising mineral

Thaumasite

• first described in 1878 in Sweden and named from the Greek, “thaumazein”, to be surprised, in reference to its unusual composition with carbonate, sulfate and hydroxysilicate anions
• Formula: Ca₃Si(OH)₆(CO₃)(SO₄)
• Space group: P6₃ (No. 173)
• Crystal system: hexagonal
• Crystal class: 6
• Lattice parameters: a = b = 11.0538 Å, c = 10.4111 Å, α = β = 90°, γ = 120°

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

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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).)

• CaO₈ polyhedra (blue)
• SiO₆ octahedra (orange)
• SO₄ tetrahedra (yellow)
• CO₃ trigonalplanar coordination (gray)
• Oxygen (red)
• Hydrogen (white)

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

https://skfb.ly/6urWZ

Samsonite

• Named after its type locality, the Samson Vein of Andreasberg silver mines, Harz Mountains, Germany.
• Formula: Ag₄MnSb₂S₆
• Space group: P2₁/n (No. 14)
• Crystal system: monoclinic
• Crystal class: 2/m
• Lattice parameters: a = 10.3861 Å, b = 8.1108 Å, c = 6.6630 Å, α = γ = 90°, β = 92.639°

 

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Picture: Christian Rewitzer  | CC BY-SA-3.0

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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).)

• MnO₆ octahedra (purple)
• SbS₃ trigonal pyramids (blue)
• AgS₄ distorted tetrahedra (gray)
• AgS₃ trigonal-planar coordination (green)
• Sulfur (yellow)

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

https://skfb.ly/69Hqz

Rodalquilarite

• Named after its type locality, the Rodalquilar gold deposit, Almeria, Spain
• Formula: Fe₂(TeO₂OH)₃(TeO₃)Cl
• Space group: P-1 (No. 2)
• Crystal system: triclinic
• Crystal class: -1
• Lattice parameters: a = 5.103 Å, b = 6.653 Å, c = 9.012 Å, α = 73.40, β = 78.03° γ  = 76.76°

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Picture: Christian Rewitzer  | CC BY-SA-3.0

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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 (brown)
• TeO₃ trigonal pyramids (blue)
• Oxygen (red)
• Hydrogen (white)
• Chlorine (green)

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

https://skfb.ly/69DIu

Pascoite – a mineral with decavanadate anions

Pascoite

• Named after its type locality Pasco Province, Peru
• Formula: Ca₃V₁₀O₂₈ · 17 H₂O
• Space group: C2/m (No. 12)
• Crystal system: monoclinic
• Crystal class: 2/m
• Lattice parameters: a = 19.586 Å, b = 10.141 Å, c = 10.911 Å, α = γ  = 90°, β = 120.815°

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

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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).)

 

• Clusters of Decavanadate anions [V₁₀O₂₈]^6- (orange)
• CaO₇ polyhedra (blue)
• Oxygen (red)
• Hydrogen (white)

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

https://skfb.ly/696Kr

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, α = γ = 90°, β = 99.11°

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Picture: CC BY-SA 3.0 | Christian Rewitzer

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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

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°

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

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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).)

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