The best people to ask are of course those in South Africa ;-). If no one closer by has anything lying around, I can see what I can find for you over here. We can also discuss this directly (email: [email protected]).

There are however also people in the GeoForschungsZentrum who have South African contacts, so perhaps they have anything they want to dispose of.

Dear Johannes,

in the rock collection of the Institute of Geology, University of Stuttgart, we had some larger specimens of the South African quartz conglomerates. Today, the Institute is closed and the rock collection is liquidated.

The quartz conglomerates from Witwatersrand do not only contain detritial pyrite but also uraninite, sometimes to a significant amount, and can be highly radioactive in these cases. In our rock collection, we wanted to analyze the grade of activity of some radioactive minerals from Scandinavia by a scintillometer but this was not possible, because the signal of the Witwatersrand uraninite-bearing conglomerate in the rock cabinet nearby was more intense.

Accordingly, I recommend careful handling with this type of rock, in particular, in the case of teaching purposes and stone working.

Cheers,

Elmar

Dear Johannes,

It would be a great embarrassment for the custodians of the region Potsdam / Berlin, when they could not provide a corresponding specimen for you and your educational purposes! For example, from the universities or museums: Research Centre for Geosciences in Potsdam, Free University of Berlin, Technical University of Berlin, Berlin Museum of Natural History, Bundesanstalt für Geowissenschaften und Rohstoffe, and so on.

Best regards,

Guenter

Dear all,

thank all of you for your immediate answers!

Dear Dr. Elburg,

I very appreciate your offer and will contact you via email.

Dear Elmar,

thank you for your warning. I know that, beside other heavy minerals, uraninite can be found within these rocks (and I'm fascinated by the radiogene darkening of the quartz pebbles, similar intense features inside rocks I have only seen in the vulkanite equivalents of the baltic rapakiwi granites and in some pegmatites in the Oslo region).  For sure, I will handle such samples with all the attention they need.

Dear Guenter,

thank you for your answer, too. I will reply directly via internal message.

Best regards

Johannes

Dear Mr. Kalbe,

"Warum in die Ferne schweifen, wenn das Gute liegt so nah". Send an E mail to the Bundesanstalt für Geowissenschaften und Rohstoffe (Stilleweg 2, 30631 Hannover) or ring it up (0511-643-0) contact  Mr. Wise, responsible for the collection and ask for gold-quatz conglomerates. My colleagues worked through this topic all across Africa during the "gold research project". So you will not only get  specimens but you can also look up one of the "Geologische Jahrbücher Series D" to find the pertinent geologic  information for the samples. If you need further assistance let me know this.

Glückauf !

Harald G. Dill

Dear Mr. Dill,

thank you very much for your valuable suggestion! Today I was in contact with the BGR, and it seems they can help me to solve my problem.

Dear Mr. Avery,

thank you very much, too. If it doesn't work on a short distance, I will try your suggestion.

Best regards

Johannes