Acanthite on Nickeline

Crude silver-white crystals of the low temperature silver sulphide Acanthite occur as rich druses between silver-grey crystals of the nickel arsenide Nickeline.  The Acanthite forms as naturally etched rounded mounds, sometimes developing into crude wires and intermeshed acicular sticks.  The Nickeline also forms hexagonal prisms, beneath the surface of which mixed dull silver and brassy-gold Nickeline can be seen.  This large thumbnail is a good example of Acanthite and Nickeline from Medenec, in the Krušné Hory Mountains of Bohemia, Czech Republic.