Dear Udo,

They are probably so-called "polychora", historical attempts to model the fourth dimension.

I'm still trying to find similar examples in the old literature.

Best regards,

Guenter

Hi Udo,

probably an idealized representation of skeletal crystals. Look up "Fensterquarz" on www.mineralienatlas.de for some comparisons to real minerals.

bests, Florian

Dear Guenter and Florian,

thanks a lot for your suggestions, but I am not really convinced. Fensterquarz does not fit, but some kind of Polychora could be - I searched the internet intensively but did not find any of these models. Guenter did you find anything?

Best wishes,

Udo

Dear Udo,

These are quite hard nuts to crack. I've never seen these or similar parts, even though I've spent 50 years with lots of collectors, collections and museums all over the world. But I'll stick to it and keep on searching, promised. See you in Munich?

Best wishes,

Guenter

Dear Guenter,

yes, indeed very strange models. I'll take them with me to Munich on friday, 28th. Hope to see you there.

Best wishes,

Udo

Dear Udo,

Couldn't they be related to biomineralization?

Although I have no similar picture, but know that some bacteria and microorganisms make some odd-looking minerals and crystals (in a very tiny size).

For instance, please take a look at the following article:

Shaping Crystals with Biomolecules, by: James J. De Yoreo and Patricia M. Dove, Science  19 Nov 2004, Vol. 306

Kind regards,

Nima