I originally came across a reference to it in the bottom of an article on FDRs confiscation of gold I dug around and this is the best summary http://www.bankvictims.com.au/index.php/forum/welcome-mat/1697-gold-can-be-confiscated
Unfortunatley the links provided in the article no longer work however there are other numerous not as thorough articles out there. The main point however is the australian government already has legisalation in place to confiscate gold. The one below covers the same ground
or this from the act itself
mce-anchorPart IV—Gold
mce-anchor40 Operation of Part
(1) This Part shall not be in operation except as provided by this section.
(2) Where the Governor‑General is satisfied that it is expedient so to do, for the protection of the currency or of the public credit of the Commonwealth, the Governor‑General may, by Proclamation, declare that this Part, or such of the provisions of this Part as are specified in the Proclamation, shall come into operation, and this Part, or the provisions so specified, shall thereupon come into operation.
(3) Where the Governor‑General is satisfied that it is no longer expedient, for the protection of the currency or of the public credit of the Commonwealth, that this Part, or any of the provisions of this Part, should remain in operation, the Governor‑General may, by Proclamation, declare that this Part, or such of the provisions of this Part as are specified in the Proclamation, shall cease to be in operation, and thereupon this Part, or the provisions so specified, shall cease to be in operation.
