66 LARAMIE BASIN, WYOMING. 
was procured from very soft sandstone of the Casper formation quar- 
ried at a point 3 miles east of the city. The material was nearly 
pure silica with but a slight trace of iron and a small amount of car- 
bonaceous matter. 
CLAY. 
The alluvial deposits contain clays, especially in the wide portions 
of the valleys of Laramie and Little Laramie rivers. The Morrison 
and Benton formations and the lower part of the Montana consist 
mainly of clay shales, and the Chugwater formation contains much 
sandy red clay. Bricks have been made from the alluvial clays at 
some places, and for the last few years brickworks a short distance 
west of Laramie have been manufacturing brick from lower shales of 
the Benton excavated in sec. 36, T. 16 N., R. 74 W. The product 
is a light reddish yellow brick of very pleasing appearance, which 
stands a pressure of 5,400 pounds to the square inch. It has been 
used in several buildings in Laramie, including the new Carnegie 
Library. 
LIMESTONE. 
A very large amount of limestone in the Casper formation along 
the west slope of the Laramie Mountains and in the lower portion 
of the Chugwater formation can be utilized for flux and lime. Much 
of the limestone in the Casper formation contains carbonate of mag- 
nesia and various impurities, but some of the upper beds are of supe- 
rior quality; the Forelle limestone also appears to be good in places. 
Limestone occurs in the Morrison formation in beds from 6 inches 
to 2 feet thick, but its quality has not been tested. The top lime- 
stone of the Casper formation has been worked to a moderate extent 
in a quarry 2 miles east of Laramie, reached by a spur from the Union 
Pacific Railroad. At first it was used for glass making at Laramie? 
but it is now shipped for making lime for beet-sugar refining. The 
following analysis has been published: 
Analysis of Casper limestone quarried 2 miles east of Laramie . 
[Analyst unknown.] 
Calcium carbonate (CaC0 3 ) 98. 83 
Magnesium carbonate (MgC0 3 ) 45 
Iron carbonate (FeC0 3 ) 02 
Iron bisulphide (FeS 2 ) 10 
Alumina (A1 2 3 ) 43 
Silica (Si0 2 ) 05 
COPPER. 
Numerous prospect pits are scattered over the outcrop of the 
Casper formation and the granite east of Boulder Ridge and south 
of Tie Siding. These have all been sunk in search of copper, largely 
for the reason that several masses of float native copper weighing as 
much as 20 pounds have been found. Most of the prospects in the 
