Region
Powder River Basin (Wyo. and Mont.)
26
California
21
Colorado
12
Nevada
12
Texas
12
Arizona
11
New Mexico
11
Utah
9
Alaska
7
Wyoming
7
Idaho
6
North America
6
Kansas
5
Montana
5
Colorado Plateau
4
Front Range (Colo. and Wyo.)
4
Kentucky
4
Middle West
4
Ohio
4
Virginia
4
West (U.S.)
4
Carbon County
3
Kern County
3
Pyramid Lake
3
Pyramid Lake (Nev.)
3
United States
3
Brazil
2
Butte County
2
Central
2
Clear Creek County
2
Clearwater County
2
Cochise County
2
Geauga County
2
Georgia
2
Gilpin County
2
Gunnison County
2
Idaho Batholith (Idaho and Mont.)
2
Inyo County
2
Jackson Hole Region
2
Keweenawan Rift
2
Maine
2
Mesaverde Group
2
Minnesota
2
Missouri
2
Moose River
2
Mora County
2
North Dakota
2
Nye County
2
Park Range (Colo. and Wyo.)
2
Portage County
2
more ...