Sentence:  The Secretary of the Interior shall submit a report of his findings , together with recommendations for an effective safety program for metal and <WSD>nonmetallic</WSD> mines ( excluding coal and lignite mines ) based upon such findings , to the Congress not more than two years after the date of enactment of this Act . 
Meaning of the word marked with <WSD> tags:  not containing or resembling or characteristic of a metal