58 LARAMIE BASIN, WYOMING. 
In the SW. J sec. 2, T. 16 N., R. 73 W., 5 miles northeast of Laramie, 
gypsum crops out at the northern foot of a small hill. Several test 
pits show a thickness of 9 or 10 feet of gypsum of excellent quality. 
GYPSITE. 
Several valuable deposits of gypsum earth, or gypsite, resulting 
from the disintegration and redeposition of the rock gypsum, are 
present in the Laramie Basin. The material usually contains about 
80 per cent of gypsum, but the percentage varies. 
An extensive body of gypsite is worked by the Acme Cement Plaster 
Company just south of Laramie. The deposit covers almost the whole 
of sec. 4 and has a depth of 9 feet where worked. The upper 7 feet is 
pure gypsite, beneath which is a 5-inch red layer underlain by a foot 
or more of white gypsite resting upon gravel and red clay. The 
gypsite is in a finely divided state and goes directly to the calcining 
kettles without grinding or screening. It contains about 20 per cent 
of impurities, such as sand, clay, and limestone, but these do not 
interfere with its use for cement plaster. No plaster of Paris is made 
at this mill. 
Another large deposit owned by the Acme Cement Plaster Company 
occupies almost all of sec. 4, T. 16 N., R. 73 W., lying east of the 
county road and overlapping the southern part of sec. 3. 
Other smaller deposits in the vicinity of Laramie comprise one 
south of Spring Creek, southeast of the fair grounds; another in the 
SE. I sec. 28, T. 16 N., R. 73 W., a mile northeast of Laramie; and a 
third along Soldier Creek extending 1 mile below and 2 miles above 
the site of old Fort Saunders. A small deposit occurs in the valley of 
Harney Creek in the NE. \ sec. 21, T. 14 N., R. 73 W., a mile south- 
east of Red Buttes; and another is worked by the Consolidated Plaster 
Company at Red Buttes. The latter lies just west of the mill and 
has a depth of 5 or 6 feet. In the manufacture of plaster of Paris the 
rock gypsum is sorted, the rejected rock being mixed with the gypsite 
for the manufacture of cement plaster. 
An extensive bed of gypsite occupies the lower 2 miles of the valley 
of Willow Creek to its junction with Lone Tree Creek and extends 
2 miles down Fivemile Creek. Another gypsite deposit occupies 
portions of sees. 33 and 34, T. 14 N., R. 74 W. 
Many of the gypsite beds above described have been carefully bored 
and tested by parties interested in their location, and others have been 
located by their effect on the vegetation growing over them. 
BENTONITE. 
OCCURRENCE AND CHARACTER. 
The variety of clay known as bentonite occurs in many localities 
in Wyoming, usually appearing as a bed in the lower portion of the 
Benton formation. In the Laramie Basin it occurs near the member 
