Castle Minerals stocks have soared after it announced a significant new gold discovery at its Baayari prospect in north-west Ghana.

Castle announced today that first pass drilling had intersected a strong zone of gold mineralisation, including 55 metres at 1.82 grams per tonne of gold from 15m, and 5m at 6.64g/tonne gold from surface.

Castle said the results were the most significant to date at Baayiri, and provided encouragement that substantial gold mineralisation could be present.

Another drill rig is being mobilised to site, and additional drilling will commence this week, Castle managing director Mike Ivey said in a letter to shareholders today.

"We believe we have just scratched the surface of what we hope will be a major new gold discovery on ground that has never previously been explored," Mr Ivey said.

At 11:23AM its stock had jumped 36.6 per cent, to trade at 41 cents.

Mr Ivey said the discovery was a vindication of the company's Ghana exploration strategy.

The disseminated nature of the mineralisation is suggestive of a broad and possibly large-scalle pervasive mineralising event providing encouragement that this is a substantial deposit," Mr Ivey said.

"The width, grade and near surface nature of the intercept has obvious economic implications and we are keen to recommence drilling as soon as possible to determine the exact geometry and scope of the mineralisation intercepted."

The Baayari prospect is part of Castle's 10,000 square kilometre Wa project in Ghana.

An 80,000m exploration program is focusing on four regional scale prospect corridors, including Baayiri.

"These initial results at the Baayiri prospect validate our commitment to develop the company and drive value for our shareholders through ground-up exploration in Ghana," Mr Ivey said.