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[Herman van Dennebroek]

Dear Tsumeb enthusiasts,
In preparing a lecture on pseudomorphoses I also include some Tsumeb specimens.
The photos I send now shows a piece that I have in my collection for over 30 years. It can be seen that the Zn-olivinite (earlier called cupro adamine) has been partially or completely converted into a brown-red crystal. The question is what is the substitute mineral. At first I thought of hematite or an iron hydroxide. But the streak color is a bit lighter (less brown) than that of hematite. The structure of the brown-red material is finely grained. I found the same fine-grained material on a small specimen with mainly carminite. The carminite has filled cavities in the form of a fine-ray layers.
Given the chemical composition of carminite, this mineral is in my opinion more suitable to replace the Zn olivinite than hematite.
I like to read your opinions,
Greetings Herman