Foreign ownership law and foreign takeover ?, page-3

Not really the easiest subject to dig into I've found, going off of Aussie history I would say that we nearly always sell out

Some info found mentioned something about Freetrade agreements (FTA) and certain cost figures for notifying prior to acquiring a percentage of a company.

http://firb.gov.au/files/2015/09/Australias_Foreign_Investment_Policy_December_2015_v2.pdf

1. Non-government foreign investors
   
   Business acquisitions
   
   Foreign persons must get approval before acquiring a substantial interest (at least 20 per cent) in an Australian entity that is valued above $252 million.2
   
   Consistent with Australia’s FTA commitments, a $1,094 million threshold applies to agreement country investors from Chile, China3, Japan, Korea, New Zealand and the United States (agreement country investors). However, the $252 million threshold applies to these investors if investing in sensitive businesses.

Tenements

Foreign persons must get approval to acquire an interest in a mining or production tenement, regardless of value.

Agreement country investors only need to apply for mining or production tenements where the value of the interest is more than $1,094 million