190 CEMENT MATERIALS AND INDUSTRY. [bull. J4:j. I 
LIMESTONES. 
Of the various limestone formations that outcrop in different parts 
of Michigan three have been utilized in the manufacture of Portland 
cement, while another formation yields limestones which have not so 
far been utilized, though low in magnesia and otherwise satisfactory I 
as cement materials. The four limestone groups above noied will be 
described separately. 
DUNDEE LIMESTONE. 
This formation occurs at the base of the Devonian system, and, 
although usually concealed beneath glacial drift and surhcial deposits, \ 
conies to the surface, as is indicated on the map (PI. VII), in a belt f 
from about 2 to 9 miles wide, trending northeast and southwest across J 
Wayne, Monroe, and Lenawee counties, in the southeastern corner of ! 
the State. The same formation occurs also at the extreme northern nl 
end of the southern peninsula and on Mackinac and neighboring, 
islands, as well as in the adjacent portion of the northern peninsula, j 
The purest layer of limestone in the Dundee thus far discovered is -J 
extensively quarried at Sibley and Bellevue, near Trenton, in Wayne j 
County, and is used in the manufacture of sodium bicarbonate, soda j 
ash, and caustic soda near Detroit. The finely powdered calcium car- 
bonate, resulting as a by-product from the manufacture of caustic jl 
soda, is used by the Michigan Alkali Company for making Portland 
cement at Wyandotte. This same limestone, on account of its unusual ij 
purity, is also extensively used in the, manufacture of beet sugar. 
The Dundee formation contains several beds of limestone, most \ 
of which, however, carry too high a percentage of magnesia to per- 
mit their use in making Portland cement under the standard now J 
required in the composition of the finished product. Thus far only ; 
one layer, the celebrated 9-foot bed, best exposed at the Sibley quar- 
ries, described below, has been found sufficiently pure to be utilized 
in the industries mentioned above. The composition of the rock 
quarried at Bellevue and used by the Michigan Alkali Company at 
Wvandotte, is as follows: 
Analysis of a limestone of the Dundee formation at Bellevue. 
1 Analyst, < ). Button.] 
Silica (Si0 2 ) 0.60 ! 
Iron oxide (Fe 2 O s )l ;{ Q4 
Alumina (A1 2 3 ) / 
Calcium carbonate (CaC0 3 ) 95. 24 ' 
Magnesium carbonate (MgC0 3 ) 1 . 00 
Total 99. 88 
