You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For consistency, answers should be in all lower cased letters.

Category: ROCKS & MINERALS 
Clue: A mixture containing antimony is sprayed on canvas to render it this
fireproof

Category: IN THE PAST MILLENNIUM 
Clue: In 1066 this group conquered England
normans

Category: SEAN SONG 
Clue: The rap on him is he's sometimes "Puffy"

sean combs