Region
Colorado
46
Utah
39
Wyoming
32
Alaska
24
South Dakota
23
Idaho
20
Colorado Plateau
19
Montana
16
United States
15
Phosphoria Formation
12
San Juan County
12
Arizona
11
Florida
10
Nevada
10
Fall River County
9
New Mexico
9
Custer County
8
New York (State)
8
Black Hills (S.D. and Wyo.)
7
Gilpin County
7
Jefferson County
7
West (U.S.)
7
Clear Creek County
6
Carbon County
5
Crook County
5
Seward Peninsula
5
Brazil
4
Garfield County
4
San Miguel County
4
Suffolk County
4
Sweetwater County
4
Weston County
4
Emery County
3
Georgia
3
Gila County
3
Hardee County
3
Hillsborough County
3
Kansas
3
Montrose County
3
Pennsylvania
3
Polk County
3
San Juan Mountains (Colo. and N.M.)
3
Bahia (State)
2
California
2
Caribou County
2
Coconino County
2
Dawson County
2
Dolores County
2
Fremont County
2
Front Range (Colo. and Wyo.)
2
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