whinstone noun. 
['wɪnstǝʊn] E16.[from WHIN noun1 + STONE noun.]1.  Any of various hard dark-coloured rocks or stones, 
esp. compact igneous rocks, as basalt, dolerite, etc.; greensand, chert, etc. 
E16.2.  A boulder or slab of this. 
L16.  [TahlilGaran] English Dictionary ▲