The answers to the clues below will have something in common:

Exact duplicate
Fierce determination
Symbol of one born to a life of privilege
Young woman who marries old man, perhaps
Breathing aid equipment
It's lighter than air
Las Vegas has thousands of them

Answers:

Carbon copy
Iron will
Silver spoon
Gold digger
Oxygen tank
Helium balloon
Neon signs

Credit:
LA Times Crossword
September 17, 2008
Norma Steinberg
MINED OVER MATTER