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Photos of epitaxy - (16)
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Roger Warin




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PostPosted: Jan 17, 2016 00:01    Post subject: Re: Photos of epitaxy - (16)  

Hi,

A case of epitaxy forgotten: hematite on rutile.
Epitaxial assemblies are sometimes surprising. So while such epitaxy of rutile on hematite is well known, it is not the same for the reverse assembly, i.e. hematite upon rutile. This is of course always the same epitaxy law.
The rarity of this latter possibility is related to the relative abundance of iron versus titanium. Iron is often more abundant than titanium.
This assembly of hematite on rutile has been discovered in 1997 by Alain Robert, for the 1st time in Niedermendig (Eifel, Germany). But only few micromounts were discovered on this occasion.
Afterwards, a fabulous find was made in Madagascar in 2005 and published in “Le Règne Minéral" - 2008.
Locality: Tetikana, area of Ambatofinandrahana-Mandrosonoro. It is in the southwest of Ambositra.
I had the opportunity to describe this fine epitaxy (with Alain Robert and Prof Frederic Hatert – Univ.Liege, B) in the French magazine “Le Règne Minéral", No. 124 (July-August) 2015.
Roger.



Hem-Rut#1-A&B2&C1c_R.jpg
 Mineral: Hematite, Rutile
 Locality:
Tétikanana, Ambatofinandrahana, Ambatofinandrahana District, Amoron'i Mania Region, Fianarantsoa Province, Madagascar
 Dimensions: 11 mm
 Description:
epitaxy of hematite on rutile
 Viewed:  3313 Time(s)

Hem-Rut#1-A&B2&C1c_R.jpg


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Tobi




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PostPosted: Jan 17, 2016 04:04    Post subject: Re: Photos of epitaxy - (16)  

I should mention my Chinese galena specimen from Rucheng Mine, already discussed in Strange kind of crystal growth of galena and sphalerite
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Roger Warin




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PostPosted: Feb 19, 2016 10:54    Post subject: Re: Photos of epitaxy - (16)  

This small specimen is a new epitactic intergrowth of hematite on rutile, which has been discovered by Alain Robert in 1997 at Niveligsberg, Drees, Germany (Photo by Eddy Van Der Meersche). The sample consists in two rutile prisms twinned along (031), showing hematite lamellae on their terminations. These lamellae are oriented in two directions at 90° from each other, in agreement with the tetragonal symmetry of the rutile crystals. In a article published in Le Règne Minéral, Nr 124 (2015), Frederic Hatert and me describe this intergrowth. It is compared with the classical rutile-on-hematite epitaxy, illustrated by historical samples from the collections of the University of Liège, Belgium. The epitaxy phenomenon is described in its historical context, with a peculiar focus on the relationships between the crystal lattices of rutile and hematite.

The epitaxy phenomenon implies the existence of compatibility to some degree between different crystalline lattices. It is also essential that cohesion links are established between the interphase atoms. Since the epitaxial rutile on hematite is common and well known, why could not it be the opposite, namely a crystallization of rutile on hematite under the laws of the epitaxy? The reverse situation is of course possible, but it is unlikely because in most deposits, iron is dominant compared to titanium. The observation of this Niveligsberg epitaxy therefore indicates a geochemical context particularly enriched in Ti versus the iron content (volcanic rocks).
The same situation occurs in Madagascar (Tetikana, Ambatofinandrahana, Fianarantsoa Province), where exceptional and very rare specimens were discovered (around 2006) (see Thomas, in Le Règne Minéral 2008) in this region where the pegmatites alongside volcanics.

As shown in the figure when crystallographic axes "a" of rutile and hematite are parallel, there is a triple cell of rutile in which the nodes are in approximate agreement with hematite nodes (hematite a = 5.30 Å and c = 13.75; rutile: a = 4.59 Å and c = 2.96).



01-Hema_Ruti_Eddy1_R.jpg
 Mineral: Hematite on Rutile - epitaxy
 Locality:
Niveligsberg Mountain, Kelberg, Eifel, Rhineland-Palatinate/Rheinland-Pfalz, Germany
 Dimensions: FOV = 3 mm
 Description:
New find in 1997
 Viewed:  3004 Time(s)

01-Hema_Ruti_Eddy1_R.jpg



02-Hema-Ru#1518_R.jpg
 Mineral: Rutile on Hematite - epitaxy
 Locality:
Grischun (Grisons; Graubünden), Switzerland
 Dimensions: 4 cm
 Description:
Coll. G. Cesàro (ULG) about 1900
 Viewed:  3001 Time(s)

02-Hema-Ru#1518_R.jpg



05-EPIhema-1.jpg
 Mineral: Hematite on Rutile - epitaxy
 Locality:
Niveligsberg Mountain, Kelberg, Eifel, Rhineland-Palatinate/Rheinland-Pfalz, Germany
 Description:
SEM
 Viewed:  3006 Time(s)

05-EPIhema-1.jpg



06-EPIhema-V7.jpg
 Mineral: Hematite on Rutile - epitaxy
 Locality:
Niveligsberg Mountain, Kelberg, Eifel, Rhineland-Palatinate/Rheinland-Pfalz, Germany
 Description:
SEM
 Viewed:  3015 Time(s)

06-EPIhema-V7.jpg



Réseau_epitaxie.jpg
 Description:
two Crystal lattices
 Viewed:  2997 Time(s)

Réseau_epitaxie.jpg



08-Hem-Rut#1-A&B2&C1c_R.jpg
 Mineral: Hematite on Rutile - epitaxy
 Locality:
Tétikanana, Ambatofinandrahana, Ambatofinandrahana District, Amoron'i Mania Region, Fianarantsoa Province, Madagascar
 Dimensions: 1 cm
 Description:
very rare
 Viewed:  3022 Time(s)

08-Hem-Rut#1-A&B2&C1c_R.jpg


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Pete Richards
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PostPosted: Feb 19, 2016 13:07    Post subject: Re: Photos of epitaxy - (16)  

Very nice, Roger! Great to see the epitaxy theme active again!
_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
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Roger Warin




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PostPosted: Feb 19, 2016 16:38    Post subject: Re: Photos of epitaxy - (16)  

Pete thank you. Your opinion honors us.
Roger.
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Roger Warin




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PostPosted: Feb 20, 2016 01:25    Post subject: Re: Photos of epitaxy - (16)  

Hi,
Two other SEM pics of epitaxy of hematite on rutile, from Niveligsberg (Eifel).
Take a look at the general site of our club.
http://www.agab.be
Roger.



007-EPIhema-V6.jpg
 Mineral: Epitaxy of hematite on rutile
 Locality:
Niveligsberg Quarry, Niveligsberg Mountain, Kelberg, Eifel, Rhineland-Palatinate/Rheinland-Pfalz, Germany
 Description:
 Viewed:  2907 Time(s)

007-EPIhema-V6.jpg



008-EPIhema-V3.jpg
 Mineral: Epitaxy of hematite on rutile
 Locality:
Niveligsberg Quarry, Niveligsberg Mountain, Kelberg, Eifel, Rhineland-Palatinate/Rheinland-Pfalz, Germany
 Description:
SEM
 Viewed:  2914 Time(s)

008-EPIhema-V3.jpg


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Roger Warin




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PostPosted: Feb 20, 2016 08:10    Post subject: Re: Photos of epitaxy - (16)  

Hi,
Another classic epitaxial growth of rutile on hematite.
Roger.



009Hematite-3a_R.jpg
 Mineral: Epitaxy of rutile on hematite
 Locality:
Jerg Drecht, Cavradi, Curnera Valley, Tujetsch (Tavetsch), Vorderrhein Valley, Grischun (Grisons; Graubünden), Switzerland
 Dimensions: 2 cm
 Description:
 Viewed:  2867 Time(s)

009Hematite-3a_R.jpg


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Jesse Fisher




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PostPosted: Nov 02, 2017 00:15    Post subject: Re: Photos of epitaxy - (16)  

Epitaxial albite on microcline


F182r.jpg
 Mineral: Albite, Microcline
 Locality:
Organ Mountains, Organ District, Doña Ana County, New Mexico, USA
 Dimensions: 14x8x3 cm overall size
 Description:
 Viewed:  262 Time(s)

F182r.jpg


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Pete Richards
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PostPosted: Nov 02, 2017 09:00    Post subject: Re: Photos of epitaxy - (16)  

More epitaxy...


Tainiolite 5a.jpg
 Mineral: Tainiolite epitactic on Arfvedsonite
 Locality:
Poudrette Quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada
 Dimensions: Field of view 3.5 mm
 Description:
composite of 14 images
 Viewed:  221 Time(s)

Tainiolite 5a.jpg


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