L’Estrange has acted as secretary of the Department of Foreign Affairs and Trade and is currently head of the National Security College at the Australian National University in Canberra and director of the University of Notre Dame.
He will join the nominations committee.
Copper Strike has restructured its board, with Barrie Laws and John Dunlop to resign as directors.
Tom Eadie will remain executive chairman but on a reduced salary, while Brendan Jesser and Mark Hanlon will join the board.
Frank Knezovic has been appointed as non-executive chairman of Discovery Africa and Argosy Minerals.
Stellar Resources founding executive chairman Tom Burrowes has resigned.
Current CEO Peter Blight has been appointed as managing director.
Wally Borovac has been appointed as MD and CEO of Micromine.
Arunta Resources says Neil Biddle will assume the role of MD while Angus Edgar will step down to a non-executive directorship.
Edwin Zemancheff has resigned as a director of Hillgrove Resources after four years on the board.
The company will not replace him.
George White has resigned as a director of Diatreme Resources after eight years of service.
Kasbah Resources has appointed finance executive Gabrielle Moeller to the board.
Ralph Stagg has resigned as a director of Stratum Metals.
Argentina Mining has received a shareholder requisition notice seeking to remove Eduardo Videla as a director.
Finally, Damian Hogue has resigned as a director of Sphere Minerals.