Sentence:  Subject to the limitations of this Act , the Secretary shall make stabilization payments to small domestic producers upon presentation of evidence satisfactory to him of their status as such producers and of the sale by them of newly mined ores , or <WSD>concentrates</WSD> produced therefrom , as provided in this Act . 
Meaning of the word marked with <WSD> tags:  the desired mineral that is left after impurities have been removed from mined ore