Shares in Glencar Mining rose by over 60 per cent after Gold Fields made a £28 million sterling (€32 million) offer for the company.
Shares in the stock rose to 9 at 2.55pm, marginally below the 9 pence offer level issued by Gold Fields.
The companies said the offer represented a premium of 105 per cent over yesterday's closing price of 4.38 pence.
Seán Finlay, Glencar chairman, said the offer was being unanimously recommended as it was in "the best interests of all shareholders".