Mineralogie křemenných žil ložiska cínových rud Hřebečná u Abertam v Krušných horách (Česká republika)

Abstract

An extraordinary rich mineral assemblage (more than 35 determined mineral species) has been discovered in quartz greisen mineralization found at dump material of the abandoned Mauritius mine. This mine is situated about 1 km N of the Hřebečná village, 16 km N of Karlovy Vary, Krušné hory Mountains, Czech Republic. The studied mineralization with its textural and mineralogical character differs significantly from the usual fine-grained greisens mined in this area. The primary mineralization is represented by coarse-grained quartz and fluorapatite with sporadic zircon, monazite-(Ce), xenotime-(Y) and very rare cassiterite. Besides common sulphides (arsenopyrite, chalcopyrite, pyrite, sphalerite, tetrahedrite-group minerals), Bi-sulphosalts (aikinite, bismuthinite, berryite, cuprobismutite, emplectite, wittichenite) were determined. Members of the tetrahedrite group also contain increased amounts of Bi - in addition to Bi-rich tennantite-(Zn) and tennantite-(Fe), microscopic zones represented by the not approved Bi-dominant analogue of tennantite („annivite-(Zn)“) were also found. The primary mineralization was intensively affected by supergene processes. Chalcopyrite and sphalerite are replaced by Cu sulphides - especially anilite and digenite, and more rarely by geerite, spionkopite and covellite. Some of the fluorapatite grains in the vein quartz were decomposed and mrázekite, mixite, libethenite, pseudomalachite, hydroxylpyromorphite, metatorbernite as well as rare dzhalindite crystallized in the resulting cavities. However, the most abundant supergene phases are the minerals of the alunite supergroup - crandallite, goyazite, plumbogummite, svanbergite and waylandite. The detailed descriptions, X-ray powder diffraction data, refined unit-cell parameters and quantitative chemical composition of individual studied mineral phases are presented.

On the matildite–bohdanowiczite solid-solution series

“…Tellurium is always relatively low, at 0.03 apfu on average (Table 1). The samples from the Moldava (Sejkora and Skacha, 2015) and Photo Lake (this work) deposits clearly indicate that a complete solid solution may exist, as suggested previously by Banas et al (1980) and Sejkora and Skacha (2015).…”

“…The situation with the anion site is the exact opposite: the new data for the mineral from the Photo Lake deposit (Canada), reported here, show a very significant S replacement of Se (Fig. 4), significantly more than reported previously (Banas et al, 1980;Sejkora and Skacha, 2015) thus prompting the question about a possible matildite-bohdanowiczite solid solution.…”

“…possibility of matildite-bohdanowiczite isomorphism (Sejkora and Skacha, 2015). The S substitution in bohdanowiczite from Kletno (Poland) averages at 0.17 apfu, was also interpreted to indicate the possibility of a matildite-bohdanowiczite solid solution (Banas et al, 1980).…”

“…There are two possible substitutions for Se in bohdanowiczite: S (1.86 wt.% on average, with a maximum of 5.73 wt.% at the Moldava fluorite deposit, Czech Republic; Sejkora and Skacha 2015) and Te (an average of 0.96 wt.% with a maximum of 2.40 wt.% recorded at two deposits in Russia; Kovalenker andPlotinskaya 2005 andKuznetsov et al, 2012).…”

“…However, the only possible Bi-Ag sulfide-selenide substitution (between matildite, AgBiS 2 , and bohdanowiczite, AgBiSe 2 ) has not been reported for the entire S-Se substitution range. A possible complete matildite-bohdanowiczite solid solution has been invoked previously (Banas et al, 1980;Sejkora and Skacha, 2015), however data to prove its existence are lacking. It is the purpose of this contribution to fill this lacuna by providing new data and compiling all available literature data for these two minerals.…”