Abstract

Significant selenium enrichment associated with selenides and previously unknown Ag-Pb-Sb, Ag-Sb and Pb-Sb sulfosalts has been discovered in hydrothermal ore veins in the Anthony of Padua mine near Poličany, Kutná Hora ore district, central Bohemia, Czech Republic. The ore mineralogy and crystal chemistry of more than twenty silver minerals are studied here. Selenium mineralization is evidenced by a) the occurrence of selenium minerals, and b) significantly increased selenium contents in sulfosalts. Identified selenium minerals include aguilarite and selenides naumannite and clausthalite. The previously unknown sulfosalts from Kutná Hora are identified: Ag-excess fizélyite, fizélyite, andorite IV, andorite VI, unnamed Ag-poor Ag-Pb-Sb sulfosalts, semseyite, stephanite, polybasite, unnamed Ag-Cu-S mineral phases and uytenbogaardtite. Among the newly identified sulfides is argyrodite; germanium is a new chemical element in geochemistry of Kutná Hora. Three types of ore were recognized in the vein assemblage: the Pb-rich black ore (i) in quartz; the Ag-rich red ore (ii) in kutnohorite-quartz gangue; and the Ag-rich ore (iii) in milky quartz without sulfides. The general succession scheme runs for the Pb-rich black ore (i) as follows: galena – boulangerite (– jamesonite) – owyheeite – fizélyite – Ag-exces fizélyite – andorite IV – andorite VI – freieslebenite – diaphorite – miargyrite – freibergite. For the Ag-rich red ore (ii) and ore (iii) the most prominent pattern is: galena – diaphorite – freibergite – miargyrite – pyragyrite – stephanite – polybasite – acanthite. The parallel succession scheme progresses from Se-poor to Se-rich phases, i.e., galena – members of galena – clausthalite solid solution – clausthalite; miargyrite – Se-rich miargyrite; acanthite – aguilarite – naumannite. A likely source of selenium is in the serpentinized ultrabasic bodies, known in the area of “silver” lodes in the South of the ore district, which may enable to pre-concentrate selenium, released into hydrothermal fluids during tectonic events. The origin of the studied ore mineralization is primarily bound to the youngest stage of mineralization of the whole ore district, corresponding to the Ag-Sb sequence of the ‘eb’ ore type of the Freiberg ore district in Saxony (Germany) and shows mineralogical and geochemical similarities to low-sulfidation epithermal-style Ag-Au mineralization.

Highlights

  • Kutná Hora was one of the best-known mining centres in Europe in the Middle Ages

  • In the first stage of mining, the ores of silver-rich lodes in the southern part of the Kutná Hora ore district (Figure 1a) were mined extensively

  • Before the end of the 15th century, mining activity moved from the silver-rich southern part of the Kutná Hora ore district to the northern part of this district, which had silver-bearing sulfide “pyrite-rich” ores

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Summary

Introduction

In the first stage of mining (in the 13th and 14th century), the ores of silver-rich lodes in the southern part of the Kutná Hora ore district (Figure 1a) were mined extensively. The knowledge of mineralogy of ore veins in the southern silver-rich part of the Kutná Hora ore district has so far been incomplete. Mining in this historically important part of the ore district ended in the 16th century and later explorations were carried out only on a very limited scale [3,4,5,6,7,8].

KutnáHora Ore District
Kutná Hora Ore District
Anthony of Padua Mine Near Poličany
Sampling and Analytical Methods
Characterization of Ore Mineralization of Anthony of Padua Mine
Diaphorite Ag3 Pb2 Sb3 S8
Freieslebenite AgPbSbS3
Ag-excess fizélyite Ag6 Pb14 Sb21 S48
An exceptionally
Fizélyite Ag5 Pb14 Sb21 S48
Andorite IV Ag15 Pb18 Sb47 S96
Ag-Poor Ag-Pb-Sb Sulfosalts
Pb-Sb Sulfosalts
Ag-Sb Sulfosalts
13. In comparison
Minerals of the Tetrahedrite Series
Ag-Ge-S and Ag-Cu-S sulfides
Ag-Cu-S Phases
Au-rich15
Uytenbogaardtite
Galena
Clausthalite
Discussion
Discussion of the Formation Conditions
Conclusions
Full Text
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