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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Dec 26, 2013 04:13 Post subject: 2014 - International year of crystallography: for example, pyrite. |
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2014 marks the centennial of the birth of X-ray crystallography, thanks to the work of William Henry, William Lawrence Bragg (father and son) and Max von Laue (the later was awarded the 1914 Nobel Prize in Physics for his discovery of the diffraction of X-rays by crystals).
2014 will be the International Year of crystallography. This is an opportunity to find specific crystalline forms.
The picture shows an euhedral crystal of pyrite from Elba (Rio Marina). This is a typical habit of Elba.
Roger.
Description: |
Pyrite Rio Marina - Elba Island - Italy 2 cm The cubic form is absent in this crystal. The dominant form is pyritohedron (or pentagonal dodecahedron). But some apexes are truncated by secondary forms, such as the octahedron itself slightly truncated by a diploid (or didodecahedron). A diploid has 24 faces that are formed from the splitting of the pentagonal faces on the 12 sided pyritohedron. |
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Pyrite Rio Marina - Elba Island - Italy drawing Typical habit of Elba pyrite |
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Pyrite Rio Marina - Elba Island - Italy same specimen an enlarged apex {210} pyritohedron {111} octahedron {321} diploid |
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John S. White
Site Admin
Joined: 04 Sep 2006
Posts: 1295
Location: Stewartstown, Pennsylvania, USA
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Posted: Dec 26, 2013 06:15 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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Roger Warin wrote: | Pyrite
same specimen
an enlarged apex
{210} pyritohedron
{111} tetrahedron
{321} diploid |
The triangular face is an octahedron, not a tetrahedron.
_________________ John S. White
aka Rondinaire |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Dec 26, 2013 09:23 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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Many thanks John, forgive me. It is a distraction due to age, I guess.
Roger.
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Jordi Fabre
Overall coordinator of the Forum
Joined: 07 Aug 2006
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Location: Barcelona
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Posted: Dec 26, 2013 09:29 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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John S. White wrote: | The triangular face is an octahedron, not a tetrahedron. |
Fixed
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John S. White
Site Admin
Joined: 04 Sep 2006
Posts: 1295
Location: Stewartstown, Pennsylvania, USA
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Posted: Dec 26, 2013 10:00 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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Fixed in only one place, it also needs to be fixed in the first caption.
___________________________________
True. Fixed again... ;-)
Jordi
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Rodney B Jackson
Joined: 13 Dec 2013
Posts: 12
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Posted: Dec 27, 2013 17:27 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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Naturally formed D&D dice!
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Riccardo Modanesi
Joined: 07 Nov 2011
Posts: 618
Location: Milano
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Posted: Dec 28, 2013 13:42 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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Hi Roger!
The proper name of the locality is Rio MARINA, not Marino. The specimen is very beautiful, typical of this locality. I found some of these pyrites there.
Greetings from Italy by Riccardo.
Roger Warin wrote: | 2014 marks the centennial of the birth of X-ray crystallography, thanks to the work of William Henry, William Lawrence Bragg (father and son) and Max von Laue (the later was awarded the 1914 Nobel Prize in Physics for his discovery of the diffraction of X-rays by crystals).
2014 will be the International Year of crystallography. This is an opportunity to find specific crystalline forms.
The picture shows an euhedral crystal of pyrite from Elba (Rio Marino). This is a typical habit of Elba.
Roger. |
_________________ Hi! I'm a collector of minerals since 1973 and a gemmologist. On Summer I always visit mines and quarries all over Europe looking for minerals! Ok, there is time to tell you much much more! Greetings from Italy by Riccardo. |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Dec 28, 2013 15:12 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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Many thanks, Riccardo,
Roger.
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Jordi Fabre
Overall coordinator of the Forum
Joined: 07 Aug 2006
Posts: 4900
Location: Barcelona
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Posted: Jan 06, 2014 13:06 Post subject: Re: 2014 - International year of crystallography |
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Roger Warin wrote: | 2014 marks the centennial of the birth of X-ray crystallography, thanks to the work of William Henry, William Lawrence Bragg (father and son) and Max von Laue (the later was awarded the 1914 Nobel Prize in Physics for his discovery of the diffraction of X-rays by crystals).
2014 will be the International Year of crystallography. This is an opportunity to find specific crystalline forms.... |
To know more about the International Year of Crystallography please use the IYCR official web page
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John Medici
Joined: 02 Mar 2011
Posts: 124
Location: Ohio
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Posted: Jan 11, 2014 20:16 Post subject: Re: 2014 - International year of crystallography : for example, pyrite. |
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A couple more pyrites to think about.
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Pyrite Barger Quarry, Lexington, VA, USA 2.5 cm on edge |
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Pyrite on quartz Spruce Claim, King County, WA, USA 3 cm on edge |
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_________________ field collector |
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Rodney B Jackson
Joined: 13 Dec 2013
Posts: 12
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Posted: Feb 05, 2014 17:41 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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Nature is amazing.
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John Medici
Joined: 02 Mar 2011
Posts: 124
Location: Ohio
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Posted: Feb 28, 2014 15:21 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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For those interested, Chemical and Engineering News (C&EN Vol.92,#7 (2/17/2014) )(Newscripts, last page) lists some postage stamps and crystal growing competitions celebrating IYCR.
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Don Lum
Joined: 03 Sep 2012
Posts: 2856
Location: Arkansas
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Posted: Feb 28, 2014 17:43 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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John Medici wrote: | For those interested, Chemical and Engineering News (C&EN Vol.92,#7 (2/17/2014) )(Newscripts, last page) lists some postage stamps and crystal growing competitions celebrating IYCR. |
Thank you for the information, Dr. Medici.
Don
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bob kerr
Joined: 13 Nov 2011
Posts: 537
Location: Monroeville PA
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Posted: Feb 28, 2014 18:14 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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has anyone noted the very interesting "pyrite after pyrites" from Racracancha Mine, Peru? they appear to be originally cubic pyrite replaced with another crystal form. how would you experts describe this crystal form?
thanks,
bob kerr
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pyrite after cubic pyrite Racracancha Mine, Tinyahuarco District, Cerro de Pasco Province, Pasco Department, Peru |
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Don Lum
Joined: 03 Sep 2012
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Location: Arkansas
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Posted: Mar 01, 2014 07:56 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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bob kerr wrote: | has anyone noted the very interesting "pyrite after pyrites" from Racracancha Mine, Peru? they appear to be originally cubic pyrite replaced with another crystal form. how would you experts describe this crystal form?
thanks,
bob kerr |
Very interesting, Bob. One of the dealers I met in Tucson had some in his room.
Here is his description and I quote:
Pyrite ps. Pyrite
Racracancha Mine, Tinyahuarco Dist., Pasco Prov., Pasco Dept., Peru
A very interesting specimen of pyrite that has pseudomorphed pyrite. I am fairly sure that the numerous small crystals are not epitaxial growths, as fractured surfaces on other pieces show internal voids between the replacement crystals.
Don
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Martin Rich
Joined: 15 Aug 2013
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Location: Lower Austria
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Posted: Mar 01, 2014 20:43 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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Very interesting but I think this is not a "pseudomorph" of Pyrite after Pyrite. Anyway it looks very nice!
Martin
_________________ We are living on the matrix. |
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bob kerr
Joined: 13 Nov 2011
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Location: Monroeville PA
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Posted: Mar 02, 2014 09:10 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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possibly not a true pseudomorph - but it seems that the cubic form of pyrite was replaced by another crystal form of pyrite.
so what would this be then? what is the visible pyrite crystal form?
hopefully one of our experts can clear this up.
bob
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Michael Shaw
Site Admin
Joined: 30 Apr 2008
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Posted: Mar 02, 2014 10:39 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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I have been contemplating this image since I first saw it yesterday, and I had the same impression as Martin. I don't know why you would call this a pseudomorph. The classic definition of a pseudomorph is one mineral replacing another while retaining the crystal form of the mineral being replaced. Perhaps a question of semantics, or maybe not having seen the specimen in person, but to me it looks like the original cubic pyrite crystal has a second generation overgrowth of smaller pyrites with a modified crystal form. I would be very interested to hear Peter Richards weigh in on this one. It's a very nice specimen in any case.
Michael
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Matt_Zukowski
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Posted: Mar 02, 2014 17:50 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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Looks to me that etching and recrystallization of smaller crystals on the larger crystal could produce this. If so, not a pseudomorph.
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Martin Rich
Joined: 15 Aug 2013
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Location: Lower Austria
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Posted: Mar 03, 2014 21:15 Post subject: Re: 2014 - International year of crystallography: for example, pyrite. |
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Matt, I think you are on the right way. An other possibility is, that a main xl was broken by tectonic forces. A lot of Pyrite crumbles are grown to this smaller crystals as seen on the photograph.
Martin
_________________ We are living on the matrix. |
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