May 31 (Reuters) - Highland Copper Company Inc HI.V :
* Unit acquires Rio Tinto (LON:RIO) exploration properties in Michigan, consideration for the acquisition is US$18.0 million
* Rio Tinto's unit retained 2% net smelter return on mineral interests, co has option to buy-down half of 2% NSR for $8 million Source text for Eikon: Further company coverage: HI.V