fossicking and prospecting for gold or gems is also banned in many areas under Section 7 Exemptions law of the Mineral Resources (Sustainable Development) Act 1990
1) which grants Ministers powers to ban these activities even if you own that land (includes much of the main gold mining cities such as Ballarat and Bendigo) -see GeoVic; a Miner's Right is regarded as an “Other Authority” as part of Section 55 of this Act.