Adjective
hard as a rock (not comparable)
(simile) Very hard (tough, inflexible); rock hard.
A reporter once asked me if I ever cried. I wonder if people think I'm just as hard as a rock and have no emotions at all. Diana Ross
My bones are as hard as a rock. Every time I have a biopsy, the doctors are doing hand exercises a week, ten days out. Don Baylor
But it's very difficult, I can tell you I played the Czech Open a few times and it's very difficult just to go on to a scene where the course is prepared differently when the greens are fast and he's not used to it and they're hard as a rock and he's not used to it. Ivan Lendl
There are places on a man's head that are as hard as a rock. Your head's actually stronger than your body. And you don't have too many instruments up there workin'. Joe Frazier
Perhaps, I can express more fully in verse ideas and emotions which run counter to the inert crystallized opinion - hard as a rock - which the vast body of men have vested interests in supporting. If Galileo had said in verse that the world moved, the inquisition might have let him alone. Thomas Hardy
Not often in the story of mankind does a man arrive on earth who is both steel and velvet, who is as hard as a rock and soft as drifting fog, who holds in his heart and mind the paradox of terrible storm and peace unspeakable and perfect. Carl Sandburg