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Josele
Joined: 10 Apr 2012
Posts: 407
Location: Tarifa, Spain
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Posted: Jan 15, 2017 13:49 Post subject: Epitaxial albite on microcline? |
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Recently I acquired a piece which I think could be a case of epitaxy. Maybe you can have a look and let your comment (special demand to Pete Richards!). Thank you all.
Mineral: | Elbaite + Microcline + Albite |
Locality: | Chhappu, Shigar District, Gilgit-Baltistan (Northern Areas), Pakistan | |
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Dimensions: | 11 x 9 x 4 cm |
Description: |
Besides an elbaite radial cluster, this specimen shows what seems to be albite in parallel growth on microcline. If it were an epitaxial growth, the a axis of both species should be parallel. Microcline face at front could be (010) ... |
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8352 Time(s) |
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Mineral: | Elbaite + Microcline + Albite |
Locality: | Chhappu, Shigar District, Gilgit-Baltistan (Northern Areas), Pakistan | |
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Dimensions: | 11 x 9 x 4 cm |
Description: |
... and face at right could be (-101). What I suppose is microcline (001) face, is very small, can be seen at top. The whole crystal is micro-dissolved, porous like a sponge, which makes it difficult to recognize faces. |
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8349 Time(s) |
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_________________ Josele |
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John S. White
Site Admin
Joined: 04 Sep 2006
Posts: 1295
Location: Stewartstown, Pennsylvania, USA
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Posted: Jan 15, 2017 14:53 Post subject: Re: Epitaxial albite on microcline? |
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It almost certainly is epitaxy. A really interesting piece.
_________________ John S. White
aka Rondinaire |
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Josele
Joined: 10 Apr 2012
Posts: 407
Location: Tarifa, Spain
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Posted: Jan 15, 2017 20:42 Post subject: Re: Epitaxial albite on microcline? |
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Thank you John.
Some more photos:
Mineral: | Elbaite + Microcline + Albite |
Locality: | Chhappu, Shigar District, Gilgit-Baltistan (Northern Areas), Pakistan | |
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Dimensions: | 11 x 9 x 4 cm |
Description: |
Front view of -supposedly- (010) face, c axis in vertical position. Top right face would be (-101) and top left (001), in which cleavelandite is (almost) perpendicular to that on front and right faces. |
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8218 Time(s) |
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Mineral: | Microcline |
Locality: | Chhappu, Shigar District, Gilgit-Baltistan (Northern Areas), Pakistan | |
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Dimensions: | 11 x 9 x 4 cm |
Description: |
Backside seems to have been sawed although there is not saw marks and is not completely flat. Anyway its orientation do not correspond to any face. In dissolved holes can see fibrous structures parallel to -supposedly- c-axis. Also can see some inclined lines parallel to the face at top left, which is -supposedly again- (-101). Would not be more logic that these lines were parallel to the cleavage plane (001)? But if we assume that face at top left is (001) then the orientation of epitactic cleavelandite do not fits... |
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8233 Time(s) |
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Mineral: | Microcline |
Locality: | Chhappu, Shigar District, Gilgit-Baltistan (Northern Areas), Pakistan | |
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Dimensions: | FOV about 1" |
Description: |
C-axis would be in vertical position. What about inclined lines? |
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8265 Time(s) |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1175
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Posted: Jan 16, 2017 00:09 Post subject: Re: Epitaxial albite on microcline? |
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Hi,
It is a growth with parallel axes.
Do we know the nature of the guest crystal? Albite I think.
If the two feldspars are different, it is an epitaxy.
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Josele
Joined: 10 Apr 2012
Posts: 407
Location: Tarifa, Spain
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Posted: Jan 18, 2017 14:01 Post subject: Re: Epitaxial albite on microcline? |
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I add a fluorescence photo where albite contrasts on the microcline better than in visible light:
Mineral: | Elbaite + Microcline + Albite |
Locality: | Chhappu, Shigar District, Gilgit-Baltistan (Northern Areas), Pakistan | |
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Dimensions: | 11 x 9 x 4 cm |
Description: |
Photo under long wave UV (365 nm, filtered) |
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7973 Time(s) |
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_________________ Josele |
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