As a benchmark re Rio selling coal assets in South Africa:
Any deal for the Riversdale Anthracite Colliery in KwaZulu Natal province, which is producing about 750,000 tonnes of coal a year, could value the asset at around $US150 million ($149m), he said.
http://www.theaustralian.com.au/business/mining-energy/rio-tinto-shortlists-bidders-for-south-african-coal-mines/story-e6frg9df-1226143311283