Approval of the expansion has been keenly awaited by Australian companies working in Mongolia, and is expected to dramatically improve investor sentiment toward the land-locked Asian nation. Mr Stewart will be happy to see the expansion approved but says he doesn't expect a return to the feverish days of five years ago, when Mongolia was lovingly termed "Mine-golia" and "Mon-coal-ia" by excited investors. "I am sure you are going to see people try and flood back into Mongolia for exploration, because no-one is questioning the geology and the prospectivity. It is the most sparsely populated country in the world, it has a young motivated workforce, and you are on the doorstep of the world's biggest market," he said, in reference to Mongolia's shared border with China. "But I think it will be a lot more measured. "The projects are not there to get feverish about. You get feverish about the opportunity to discover more, but that is quite a long story.

"There has been very little exploration ... so it is going to have to go into real grassroots exploration." In truth, attitudes toward Mongolia have already shifted from the fears about sovereign risk that dominated sentiment just two years ago. Mr Stewart points to the 20 international banks that in December agreed to lend $US4.4 billion to Rio for the Oyu Tolgoi expansion as an important moment for sophisticated investors. Shares in Xanadu have already risen from 7.5¢ in September to 24¢ this week, and Stewart hopes that some fresh discoveries will boost that further. Xanadu already has some promising resources on its tenements, which were purchased from the same Rio subsidiary that owns Oyu Tolgoi: Turquoise Hill Resources.

Stewart worked for Turquoise Hill's predecessor in the large drill team that made the Hugo Dummett discovery that transformed Oyu Tolgoi from a promising province to a major find. He recalls how that discovery pulled drill rigs away from the tenements that Xanadu is now exploring. "It was really the discovery of Hugo that saw the concentration of drilling move to Oyu Tolgoi," he said. Stewart's team will drill 6000 metres of exploration holes in 2016, and are hoping to find the final piece of the Kharmagtai puzzle. "It is not one particular deposit that makes it, it is generally a series or a cluster of different deposits," he said.

"Oyu Tolgoi is four deposits; we have found three deposits, we are looking for that fourth centre, and we believe discovery of that fourth centre will get the project to that next level, and that is what the exploration focus is on at the moment."