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Bariopharmocosiderite Colour Change

Last Updated: 15th Mar 2017

By Volker Betz

The recent discussion about colour change of bariopahamacosiderite https://www.mindat.org/forum.php?read,19,373867,406116#msg-406116 remembered me that I observed a colour change from green to brown at self colleted bariopharnacosiderite crystals from Clara Mine, Rankach valley, Oberwolfach, Wolfach, Ortenaukreis, Baden-Württemberg, Germany also from Point 16.1, Hohenstein, Reichenbach, Lautertal (Odenwald), Odenwald, Hesse, Germany and from Monstranzenbaum, Quarzgang Frauenstein, Frauenstein, Wiesbaden, Hesse, Germany. From the last location I colleted some small bariopharmacosiderite crystals in 1995 which changed in colour from bright green to yellow brown at dark and 30 % humidity within a year. One of the crystals was immersed in water (set to PH <2 (with HCl) at room temperure for 3 days. Its colour changed back to green with a brown core.
See Pictures below.

Bariopharmacosiderite from Frauenstein after 20 years in drawers
and after immersion in water for 3 days
Bariopharmacosiderite from Frauenstein after 20 years in drawers
and after immersion in water for 3 days
Bariopharmacosiderite from Frauenstein after 20 years in drawers
and after immersion in water for 3 days

Crystal size is 0.8 and 0.7 mm.

So there is a reason to repeat the experiment with bariopharmacosiderite from other locations.

Article has been viewed at least 1273 times.


Can you shows us pictures of the same crystal before and after water? Those are not the same crystals, so the pictures don't really make the case.

Keith Wood
19th Mar 2017 1:07pm
Volker you made hydroniumpharmacosiderite :)


Stuart Mills
29th Mar 2017 2:38am

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