(Corrects former finance director's surname in paragraph 7)

LONDON, Sept 30 (Reuters) - Trading house Noble NOBG.SI and private equity group TPG have each invested $500 million in a private mining venture led by Mick Davis, the former head of Xstrata, hoping to cash in on low valuations and a dearth of buyers for mining assets.

Davis set up his new venture, named in a statement on Monday as X2 Resources, earlier this year, after he was ousted from Xstrata following the miner's acquisition by trading giant Glencore GLEN.L , its largest shareholder.

Under the original takeover deal, Davis had been due to be chief executive of the combined Glencore Xstrata group, but a dispute over executive pay and an eventual improvement of Glencore's offer meant the end for the South African boss after a more than a decade at the helm of Xstrata.

After that abrupt exit, Davis, known as a dealmaker, moved swiftly, using Xstrata's former offices to set up what he and his investors hope will become a second Xstrata - a diversified miner he is credited with building into one of the world's largest, up from a $500 million collection of zinc and ferrochrome assets.

Davis is one of a number of mining bosses ousted in a wave of change in the sector over the past 12 months, as prices cooled, boom-year deals soured and investors began to demand austerity. Many of them, like Davis, have remained in the industry with private investment companies - hoping to cash in as major miners shed unwanted assets and few queue up to buy.

In a statement on Monday, the companies said X2 Resources planned to create a "mid-tier diversified miner and metals group", whose output would eventually be marketed by Noble, a rival of Glencore's.

The statement said Davis' team, which also includes former Xstrata finance director and long-time boss Trevor Reid, was in discussion with "a further select group" of potential investors.

Goldman Sachs acted as financial adviser to X2.

(Reporting by Clara Ferreira-Marques; Editing by Tom Bill and Louise Heavens)

((clara.ferreira-marques@thomsonreuters.com)(+44 207 542 3214)(Reuters Messaging: clara.ferreira-marques.thomsonreuters.com@reuters.net))

Keywords: X2RESOURCES/