CALX
Set to 2 different clues across 3 published puzzles, most often “Mineral residue” — The New York Times, Sunday, 28 May 2006.
4 letters
Every clue on record, most used first
- Mineral residue2 times
The New York Times — Sunday, 28 May 2006
- Metal oxideonce
The New York Times — Saturday, 8 April 2006