I have a rough citrine quartz crystal about the size of a roll of pennies. What is it worth?
It's a bit of a sneaky question, as at least one rock in 2, 3, and 4 does not have quartz in it, although others may. #1 is the right answer.
(1) Those rocks. I can't believe that the answer wouldn't have been in giant red letters in the center of your text book.
Silicon and oxygen are the most abundant elements available for mineral formation, and so silicates are the most abundant mineral type.
1 quartz is an igneous rock is my best guess
