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prcantos
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Joined: 17 Apr 2012
Posts: 243
Location: Granada (Spain)
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 Posted: Nov 11, 2014 08:36 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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Another diploid-faced pyrite crystals. It comes from Respina Mine (León, Spain).
In this case we can recognize the diploid faces as half-pentagons on the pyritohedron. The height of this diploid is really low. Home-made measurement gives 175º for the dihedral angle between adjacent trapezoidal faces, which means a {0'098 2 1} ≈ {0'1 2 1} = {1 20 10} form: near a pyritohedron, but in fact a diploid {hkl} with h ≠ k ≠ l ≠ h.
| Mineral: | Pyrite |
| Locality: | | Respina Mine, Fuentes de Respina, Puebla de Lillo, Comarca Valle de Boñar, León, Castile and León, Spain |  |
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| Dimensions: | 5.5 x 4.5 cm. |
| Description: |
| Pyrite in talc matrix. A false pyritohedron... |
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| Viewed: |
24336 Time(s) |
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| Mineral: | Pyrite |
| Locality: | | Respina Mine, Fuentes de Respina, Puebla de Lillo, Comarca Valle de Boñar, León, Castile and León, Spain | |
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| Dimensions: | 4 mm. the front edge |
| Description: |
| ... look at the line dividing the upper pentagon into two trapezoidal halves. They are in fact faces of the diploid. They appear in every 'pentagon' of this crystal, and can be detected mainly because of shining differences. |
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| Viewed: |
24300 Time(s) |
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| Description: |
| Estimated ideal form for this specimen, a {0'098 2 1} ≈ {0'1 2 1} diploid, not a pyritohedron! |
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| Viewed: |
24395 Time(s) |
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_________________
Pablo Rodríguez Cantos
Λίθον˛ον απεδοκίμασαν˛οι οικοδομουντες |
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marco campos-venuti
Joined: 09 Apr 2014
Posts: 227
Location: Sevilla
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| Posted: Nov 11, 2014 10:10 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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| Josele wrote: | I wonder which forces act to develop so asymmetrical growth in an isometric mineral.
Definitely crystallography is as complex as it is fascinating.
Thanks for your kind explanations. |
That's true Josele, look at this picture. They look as 3 monometric crystals, but only one is isometric. Crystallography is just a human approximation to nature.
-yellow crystal is a Garnet from Imilchil, Morocco
-brown crystal is a Dravite tourmaline crystal from Tomkap tourmaline mine, Yinnietharra, Western Australia
-green crystal is an Epidote crystal from Ras Koh Mts. near Kharan, Balochistan, Pakistan.
| Description: |
-yellow crystal is a Garnet from Imilchil, Morocco
-brown crystal is a Dravite tourmaline crystal from Tomkap tourmaline mine, Yinnietharra, Western Australia
-green crystal is an Epidote crystal from Ras Koh Mts. near Kharan, Balochistan, Pakistan |
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24289 Time(s) |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1232
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| Posted: Nov 23, 2014 10:07 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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This pyrite crystal seen in Munich Show was for me the top of “my” International Year of Crystallography. It is a gorgeous crystal.
Roger.
| Mineral: | Pyrite |
| Locality: | | Huanzala Mine, Huallanca District, Dos de Mayo Province, Huánuco Department, Peru | |
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| Dimensions: | 7.5 cm |
| Description: |
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| Viewed: |
24093 Time(s) |
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prcantos
Site Admin
Joined: 17 Apr 2012
Posts: 243
Location: Granada (Spain)
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| Posted: Dec 16, 2014 18:10 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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Nanisivik Mine is well known for its pyrite crystals. They show faces according many different crystallographic forms.
In this specimen you can recognize the cube, the octahedron, the dodecahedron, the trapezohedron and the pyritohedron.
| Mineral: | Pyrite |
| Locality: | | Nanisivik Mine, Nanisivik, Baffin Island, Nunavut Territory, Canada | |
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| Dimensions: | 3.5 x 2.5 cm. |
| Description: |
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| Viewed: |
23618 Time(s) |
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| Mineral: | Pyrite |
| Locality: | | Nanisivik Mine, Nanisivik, Baffin Island, Nunavut Territory, Canada | |
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| Dimensions: | 1 x 1 cm. crystal |
| Description: |
| This crystal has cubic, octahedral and dodecahedral faces. The narrow face at the bottom right belongs to the trapezohedron. |
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| Viewed: |
23628 Time(s) |
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| Mineral: | Pyrite |
| Locality: | | Nanisivik Mine, Nanisivik, Baffin Island, Nunavut Territory, Canada | |
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| Dimensions: | FOV 2.5 cm. |
| Description: |
| Another crystal with adds pyritohedral faces. |
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| Viewed: |
23610 Time(s) |
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| Mineral: | Pyrite |
| Locality: | | Nanisivik Mine, Nanisivik, Baffin Island, Nunavut Territory, Canada | |
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| Dimensions: | FOV 2.5 cm. |
| Description: |
| Another complex crystal. Can you guess it? |
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| Viewed: |
23643 Time(s) |
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_________________
Pablo Rodríguez Cantos
Λίθον˛ον απεδοκίμασαν˛οι οικοδομουντες |
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Martin Rich
Joined: 15 Aug 2013
Posts: 127
Location: Lower Austria
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| Posted: Dec 30, 2014 15:35 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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The international year of crystallography is still running!
| Mineral: | Pyrite, Calcite |
| Locality: | | Stan Trg (Stan Terg, Stari Trg) Mine, Trepča Complex, Trepča Valley, Kosovska Mitrovica, Kosovska Mitrovica District, Kosovo | |
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| Dimensions: | 7.5 x 6.5 x 4 cm |
| Description: |
| Complex aggregate of rounded pyrite crystals. Only {100} is clearly identifiable. New find from 2014. |
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| Viewed: |
23512 Time(s) |
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_________________
We are living on the matrix. |
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