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: A PARIS CHRONOLOGY 
Clue: Paris was founded around 250 B.C. by the Celtic Parisii tribe, who built a settlement on an island in this river
the seine

Category: RELIGION 
Clue: One meaning of this word is any member of Christ's church, as in the Church of Jesus Christ of Latter-day ones

a saint