Amalgam zlata z novoknínského zlatonosného revíru, střední Čechy (Česká republika)
Zdeněk Medek, Jiří Sejkora, Jiří Litochleb
Silver-grey aggregates up to 0.5 mm in size were found at a placer of a nameless small stream in the NE part of the Nový Knín gold-bearing district (central Bohemia, Czech Republic). They are identified as gold aggregates (with central part: Au 89.41 - 90.77, Ag 5.81 - 6.14, Hg 0.82 - 2.47 wt. % and margins: Au 95.94, Ag 1.28, Hg 1.25 wt. %) covered by irregular coatings of gold-amalgam with composition close to formula AuHg (Au 47.30 - 53.50, Ag 0.21 - 0.56, Hg 43.81- 47.03 wt. %). Intensive Hg metasomatism of marginal part of gold aggregates took place (sub)recently in conditions of stream placer. Gold-amalgam coatings have anthropogeneous origin. The source of mercury is probably the contamination of environment in connection with using of amalgamation during processing of gold-bearing ores in past.