Ca4(Ca,Sr,K,Ba)3Cu3[Al3Si3O12]4(OH)8 · nH2O to zeolithe group
Tschörtnerite is quote MinDAT "the only currently known natural representative of the group with copper as an essential cation. Named in 1998 by H. Effenberger, G. Giester, W. Krause, H. J. Bernhardt in honor of Jochen Tschörtner (*1941) of Cologne (Germany), pharmacist, mineral collector and discoverer of the mineral.
In the late 90's a dark xenolith of the hard lave had been discovered in the lower part o Bellerberg volcano. The Ca-rich stone included layers in green black propable pyroxene and feldspar. The small pores had been coated with fibers of tobermorite and some of the caverns included very small lightblue transparent isometric crystals 100. Tschörtnerite can be find in staircase-shaped form or as single cubics. Quote G. Blaß, for more detail read latest Eifel CD by G.Blaß.
Decomposed copper containing minerals in this xenolith are chalkopyrite and cuprite.The complete paragenetic is zeolithe, willhendersonite, phillipsite, chabasite, gismondine, thomsonite, levyn und bellbergite. Much more details on Eifel-CD.
My photos here and in MinDATresults from FJ. Emmerich collection who was every weekend that year together with Jochen Tschörtner in the Eifel to collect minerals. Regarding quality please consider the very small FOV of mostly < 0.3mm.
collection & photo © 2021 by Volker Heck