Shares hit an intraday high of A80c before closing on 75c, an 87.5% premium, with just over 2.5 million shares changing hands.
The company raised $15 million in its initial public offering.
County acquired two thermal coal projects in the Powder River Basin in Wyoming, with a view to fast-track production.
The Shell Creek project has resources of 332 million tonnes, while the Miller project has a 310Mt measured resource.
The company is targeting a 1 billion tonne resource within two years and initial production of 5 million tonnes per annum by 2015 with plans to increase to 20Mtpa by 2018.
Corporate advisor Marcus Boland is an executive director and Wyoming-based geologist David Miller is a non-executive director.
Former Carabella Resources managing director Mitch Jakeman and Shell Canada consultant Steven Parker make up the company’s mining advisory panel.
