Hidden Valley is an open-pit, gold-silver mine and processing plant located in Morobe Province. It is, approximately 210 kilometres north-north-west of Port Moresby and 90 kilometres south-southwest of Lae.

The mine is a 50:50 joint venture between Harmony Gold and Newcrest Mining Limited. 

Newcrest bought an initial 30% stake in Harmony’s PNG assets in July 2008 for US$229 million and sole funded exploration, development and construction costs in the joint venture area for around US$300 million in 2009 to earn-in an additional 20%. Newcrest formally reached a 50% stake in the joint venture on 30 June 2009.