Misc: of what mineral is limestone composed of?

Questions

"--------- aren't exactly people...they're a whole lot of people trying to be one person."- F. Scott Fitzgerald?

"---------- should be read, but neither seen nor heard."- Daphne Du Maurier?

"--------- is turning one's worst moments into money."- J.P. Donleavy?

"A ------------ is one of the only pieces of evidence we have that people are still thinking."- Jerry Seinfeld (1954 - )?

"A ---------- is a person who works hard all his life to become known, then wears dark glasses to avoid being recognized."- Fred Allen (1894 - 1956)?