GRIMSLEY. | Gypsum Mines and Mills. 53 
layer. The rock is irregularly traversed by blue clay seams 
which contain a small amount of carbonate of lime. These are 
not large nor numerous enough to injure the rock for plaster, 
and in some parts of the stratum they are absent. On exposure 
to the air for some time or when crushed, the rock becomes 
very soft and snow white. 
In this Fowler mine cutters or veins occur which contain 
masses of transparent selenite crystals grown together, varying 
in size from the very smallest 
to those of several inches in 
length. This is the only mine 
in the state which yields crys- 
tals and it is especially interest- 
ing on that account. 
The section at this mine, fig- 
= 5/0'| i mestone ure 1, shows a blue limestone 
6 BlueShale bed-rock over 4 feet thick. 
== Delta Above this comes the gypsum 
fre with an average thickness of 84 
Cah feet, covered by 8 feet of red 
cine and blue shales, followed by a 
thin limestone layer and then 
May GCRBInAGoe eo 22 feet of buff shales with a 
thin stratum of shaly limestone 
about the center. On the hills to the east of Fowler’s the buff 
limestone, which occurs throughout the region, outcrops 100 
feet above the gypsum. This mine, which was located on the 
original gypsum grantof the town company, represents the old- 
eSt gypsum working in the state, and gypsum has been taken 
out from there almost continuously since the days of Coon & 
Son, though never on a very large scale. 
GREAT WESTERN MINE. 
The Great Western mine is located on the side of a bluff one 
mile north of the town of Blue Rapids and about 50 feet above 
the level of the water in the river at the railroad bridge. It is 
two and one-fourth miles southeast of the Fowler mine. The 
