Geological Counties of the U.S.

The names of these counties relate in some way to geological or mineralogical terms. Identify them.
County names may have derived from other sources e.g. individuals' names.
Populations are July 2013 Census Bureau estimates.
I've tried to include as many states as possible, so counties used may not be largest with that name.
Quiz by Roger77024
Rate:
Last updated: July 23, 2015
You have not attempted this quiz yet.
First submittedJuly 23, 2015
Times taken55
Average score28.6%
Report this quizReport
3:00
Enter answer here
0
 / 14 guessed
The quiz is paused. You have remaining.
Scoring
You scored / = %
This beats or equals % of test takers also scored 100%
The average score is
Your high score is
Your fastest time is
Keep scrolling down for answers and more stats ...
State
Population
COUNTY
Colorado
310,048
Boulder
Florida
196,399
Clay
Wisconsin
160,739
Rock
Alabama
88,845
Limestone
Pennsylvania
64,786
Carbon
Utah
46,780
Iron
Missouri
31,297
Stone
Texas
19,646
Freestone
Idaho
16,686
Gem
Minnesota
9,270
Pipestone
Oklahoma
5,867
Coal
Nevada
4,614
Mineral
Montana
3,138
Granite
Montana
506
Petroleum
+1
Level 73
Jul 24, 2015
What about Lake County, IL?
+1
Level 57
Jul 25, 2015
More geographical than geological - former will follow, I promise! I'm onto names at present e.g. Girlie Counties.