Filed from 7 published puzzles

GRANITE

Set to 7 different clues across 7 published puzzles, most often “Symbol of hardness” — The New York Times, Sunday, 27 May 2007.

7 letters

Every clue on record, most used first

Symbol of hardnessonce
The New York Times — Sunday, 27 May 2007
Countertop choiceonce
The New York Times — Thursday, 5 April 2007
Like curling stonesonce
The New York Times — Saturday, 24 March 2007
Mt. Rushmore materialonce
The New York Times — Monday, 17 October 2005
New Hampshire productonce
The New York Times — Friday, 24 January 2003
Unyieldingonce
The New York Times — Saturday, 23 June 2001
Rock for a monumentonce
The New York Times — Tuesday, 27 June 2000

Other answers to these clues

ADAMANT7 letters
DEAF4 letters
HARDLINE8 letters
IRON4 letters
IRONBOUND9 letters
NAILS5 letters
OBDURATE8 letters
RIGID5 letters
STEELY6 letters
STERILE7 letters
STERN5 letters
STRICT6 letters