By Rhodri Morgan Helium resources developer Helium Exploration has floated today on the AIM market of the London Stock Exchange. The group’s listing was oversubscribed more than threefold, raising £7.5m compared to the targeted £3.5m to £5m. The shares listed at a price per share of 10p. The firm said it has identified a series of proven helium deposits across three sites in the Ingomar Dome region of the US state of Montana, with total volumes between 856m and 2.3bn cubic feet. Net proceeds from the fundraising will be used to fund a scoping study and appraisal drilling at the Ingomar project…