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 Post subject: What it could be in garnet? Are my thoughts correct?
PostPosted: Tue Jul 05, 2016 4:13 pm 
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Posts: 170
Location: Lachine, Quebec
I received 10.34 ct color change garnet. My friend purchased this stone, listed with fantastic colors and very honestly described clarity (very included in real) gem on ebay for just $250. he wanted make sure it is garnet, so stone has been shipped to me.

RI 1.768, single refracted, SG 3.873, reacted to strong neodymium magnet, no fluorescence, naturally occurred inclusions. So it is garnet no doubt, origin is unknown (Thai seller mentioned Madagascar)

Image
Lighting conditions: Studio day light 5600K, quartz-halogen incandescent light 3200K, both mixed lights.

There are some inclusions in this garnet shows noticeable almandine int he mix. Together with rutile needles there are many inclusions I think of monazite, dark opaque figures with well visible strains caused by them.

There are some transparent crystals of quartz and apatite (my guess). Also on pictures are well visible some inclusions, about which my first thought was some kind of mica. I have fluorite with absolutely same looking inclusions... Different kinds of mica can be found in almandine, but I have no idea if they can appear in such "mix-cooked" garnet and color-change...

There are some shots of inclusions, mostly same area with same inclusions, but under different lighting conditions.

Interference on rutile needles without any polarization, just simple reflected fluorescent light. 20x, FoV 12 mm
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Dark field illumination, 100x, FoV 2.35 mm. Black with metallic lusted inclusions with strains around are what I though monazite, nice double-layer transparent rhombus is colorless mica by my thought.
Image

Same set of inclusions under shadowed dark field illumination, 100x, FoV 2.25 mm.
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Same set of inclusions under transmitted diffused light, 100x, FoV 2.25 mm.
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Same set of inclusions under transmitted polarized light, 100x, FoV 2.30 mm.
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Same set of inclusions under dark field illumination + fiber-optic illumination, 120x, FoV 1.95 mm.
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Diffused dark filed illumination, 100x, Fov 2.30 mm. Another inclusions by my thought quartz and/or apatite. One on side of longer crystal looks like cube on this picture, is 2 phase inclusions, from this point of view is very similar to same cubic structure of mica in fluorite, but...
Image

... but form other side this crystal looks already like as half of a hexagon, trimmed in length along the main axis... This picture under very high magnification is not best, I will re-do it. Diffused transmitted light, 200x, FoV 1.05 mm
Image

It would be pleasure to have my mistakes corrected if some of my thoughts are mistakes...

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All stones are alike, all stones are precious; but man sees only a few of them...
Maurice Maeterlinck


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 Post subject: Re: What it could be in garnet? Are my thoughts correct?
PostPosted: Wed Jul 06, 2016 5:09 pm 
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Joined: Wed Feb 11, 2015 5:22 pm
Posts: 170
Location: Lachine, Quebec
Some more pictures over internal inhabitants of this garnet.

Describing last picture in first post I wrote: "but form other side this crystal looks already like as half of a hexagon..." Today I spent quite a while time trying to find that "hexagon-like" view of this crystal, but found only how it looks like in real. So there is no hexagon, I was wrong, crystal is rhombus.

Dark field illumination, polarized light, 100x, FoV 2.05 mm. I am not sure why polarizing makes facets of this crystal to appear more "clear", maybe because it id double refractive, and under high magnification facets become a bit blurry..
Image

Dark field illumination, 60x, FoV 3.65 mm. There are 2 other crystals, one rhombus and one flat platelet, intersected perpendicular, both are colorless and transparent, both have their own dark and looks like non-transparent inclusions
Image

Dark field illumination + fiber optic, 100x, FoV 2.35 mm. Flat grown "up" crustal has also longish needle like dark inclusion partially located inside and partially outside of platelet.
Image

Another 2 views:

Dark field illumination, 100x, FoV 2.15 mm
Image

Dark field illumination, diffused light, 100x, FoV 1.95 mm
Image

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Maurice Maeterlinck


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