354 
CEMENT MATERIALS AND INDUSTRY. 
[bull. 24! 
NATURAL-CEMENT RESOURCES OF TEXAS, 
The analysis below has been published a as representing the average 
of the material used in making natural cement by a Texas natural 
cement plant. It is obvious that, if this statement be correct, tu 
product obtained by burning a rock of such composition can not be ji 
natural cement in any proper use of the term. It would, in fact, b 
merel} 7 a veiw weak hydraulic lime. 
Analysis of natural cement rock, Texas. 
Si lica (SiO, ) 5. 7 
Alumina ( A1 2 3 ) - - 2. 1 
Iron oxide ( Fe 2 3 ) 
Lime (CaO) 50. 4 
Magnesia (MgO) 2 1 
NATURAL-CEMENT RESOURCES OF VIRGINIA. 
For many years natural cement has been burned near Balcony Falls 
Rockbridge County, Va. The rock used is a claye}^ magnesian lime 
stone of Cambrian age, closely related geologically to that used ii 
West Virginia, and described below. 
. I nalyses of natural-cement rock, Virginia. 
Silica (Si0 2 ) 
Alumina (A1 2 ;! ) 
Iron oxide (Fe 2 3 ) ... 
Lime (CaO) 
Magnesia (MgO) 
Carbon dioxide (C0 2 ) 
1 
2 
17.38 
17.21 
| 7.80 
I 1.62 
34. 23 
24.85 
9.51, 
16.58 
30.40 
37.95 
17.: 
6.3 
Li 
29.1 
13. ( 
:;4.: 
1. Balcony Falls. E. C. Boynton, analyst. Gillmore, "Limes, Cements, and Mortars," p. 12. r >. 
2. Balcony Falls. C L. Allen, analyst. "The Virginias," vol. 3, p. 88. 
3. Average of preceding two analyses. 
NATURAL-CEMENT RESOURCES OF WEST VIRGINIA AN 
MARYLAND. 
A wide belt of magnesian limestones of Cambrian age crosses Mar 
land into the eastern part of West Virginia. Several small natural 
cement plants have been established at various times in this distric 
particularly near Antietam, Md., and Shepherdstown, W. Va. 
NATURAL-CEMENT RESOURCES OF WISCONSIN. 
Two plants in Wisconsin are engaged in the manufacture of natur 
cement from a clayey magnesian limestone of Devonian age. The* 
a Twenty-second Ann. Kept. U. S. Geol. Survey, pt. 3, p. 737. 
