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EducationBlackish Soddyite

18th Aug 2015 18:39 UTCFlorian Baur

I'm not sure if this fits more in the ID help section, so feel free to move... :)

I noticed that many Soddyites have a gray/black tint, does anyone know why this happens? It seems to be an impurity, but what exactly? I'm not sure if it's specific to Swambo Soddyites. An example can be found here: Soddyite on mindat

Sometimes this occurs in close vicinity, I have a 4x3 cm specimen that has three distinct sections: translucent yellow, opaque yellow, translucent gray/yellow.

18th Aug 2015 19:55 UTCPaul De Bondt Manager

Florian,

When U-minerals are blackish, it's mostly due to heterogenite impurities in the crystal stucture or a stain atop the crystals.

See : http://www.mindat.org/photo-376115.html

I hope this helps.

Cheers.

Paul.

18th Aug 2015 20:31 UTCFlorian Baur

Thanks Paul, I found some crystals that are split and their inside is plain yellow, so the discolouration is close to or on the surface as you suggested. Great specimen on the photo btw, you seem to have an impressive U-mineral collection. (tu)

In my specimen I noticed some small translucent cherry red crystals forming a 1 mm thick band embedded in the matrix along the fracture line. From Swambo the only mineral that is at least sometimes red is Curite. The crystals seems a bit odd to me though. Have you seen this before?

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