“SEM micrograph (BSE) mode of a polished section of an silver ore sample, found in 1980, containing dark red, partly As-rich pyrargyrite droplets disseminated a matrix of colourless quartz.
The picture shows, in the top left area, a slightly zoned grain (grey) of the unnamed Fe-analogue of argentotennantite-(Zn) (Cu- and Sb-rich) that grades into (Sb-dominant) "freibergite" (Cu- and As-rich). The white phase is galena and the matrix consists of fluorite (dark grey) quartz (black).
Note: The most Ag-rich grain reported by Kolitsch et al. (2019) (as "argentotennanite" because the IMA list of minerals at that time had a Fe-dominant formula) has the composition (Ag3.36Cu2.64)[Cu4(Fe1.61Zn0.39)](As,Sb)4S13.
The polished section also contained the ore minerals chalcopyrite (common), arsenopyrite (minor), cupropearceite, jordanite, tetraedrite-(Fe) and -(Zn), tennantite-(Fe) and -(Zn), freibergite (relatively common), gersdorffite, cobaltite, pyrite, famatinite, pearceite, polybasite and several REE minerals - synchysite-(Ce), monazite-(Ce), xenotime-(Y), fluocerite-(Ce) -, as well as scheelite.
This photo was originally published in:
Kolitsch, U., Bayerl, R. and Topa, D. (2019): Neufunde aus der Grube Clara im mittleren Schwarzwald (V). Mineralien-Welt 30 (3), 12-27 (in German).”
Uwe Kolitsch - 25th May 2019