On March 30, 2016 Bloomberg reported that Apple is “now auditing 100 percent of its suppliers for the use of conflict minerals linked to violent militia groups in the Democratic Republic of the Congo.”
This is the latest “milestone in supply chain transparency” since Apple began the process in 2010. The company “plans to spend the coming year enhancing the due diligence in its gold supply chain and working to improve incident reporting and resolution processes.”
You may read the article on the Bloomberg internet site.