Sentence:  This then is and alwayes hath ben the fashion of Worldlinges, & reprobate persons, to harden their hartes as an <WSD>adamant</WSD> stone, against anye thinge that shalbe tolde the for amendement of their lives, and for the savinge of their soules. 
Meaning of the word marked with <WSD> tags:  An imaginary rock or mineral of impenetrable hardness; a name given to the diamond and other substances of extreme hardness.