When I started examining micro minerals I came across a nice specimen hosting olive green bartelkeite. It was pure luck to find this mineral. This is what I can say now looking back at the small number of specimens I had.
This makes the species to one of the rarest member of the germanium containing minerals, even compared to the also rare schaurteite or otjisumeite.
I am happy to offer one again now after years in my upcoming auction.
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If you wish to have your specimens analysed for unknowns or checked for correctness, please visit my website. We offer EDS analysis (elemental ID) and Raman (structural information) at very competitive prices! We enjoy to work on minerals and like to invite you sharing your findings with us. Some of the work is now part of several well known databases.
http://www.mineralanalytik.de/en/
