The Department of Communications, Climate Action and Environment has refused a prospecting licence to a Canadian company that sought permission to carry out tests in Co Galway.
MOAG Copper Gold Resources had applied for a licence to prospect for base metals as well as gold and silver in Connemara.
The application was rejected after the company did not give sufficient information about its plans, following a request from the Department.
A prospecting licence entitles the holder to explore for mineral deposits and does not authorise mining of any minerals.
While the Department says such permissions generally involve non-invasive works, with minimal environmental impact, there was significant disquiet in Connemara about the possible longer term implications.
Today's decision has been welcomed by the Green Party.