Historical clue formulations

• Mount Rushmore's makeup — 2024-10-25
• Kind of rock for which New Hampshire is known — 2020-03-02
• Tombstone material — 2015-04-26
• Rock associated with hardness — 2012-05-21
• Symbol of hardness — 2007-05-27
• Countertop choice — 2007-04-05
• Like curling stones — 2007-03-24
• Mt. Rushmore material — 2005-10-17
• New Hampshire product — 2003-01-24
• Unyielding — 2001-06-23
• Rock for a monument — 2000-06-27