294 
CEMENT MATERIALS AND INDUSTRY. 
[bull. 243 
near the towns of Lebanon, Harris burg, Carlisle, and Chambersburg 
In Maryland the Trenton rocks occur in Washington County, while in 
West Virginia and Virginia they are extensively developed. 
Throughout this southern extension of the Lehigh rocks the Tren 
ton is not everywhere an argillaceous limestone, but it is frequently 
so, and it is always very low in magnesium carbonate. It is therefor*, 
probably safe to say that in southern Pennsylvania, Maryland, Wes 
Virginia, and Virginia the Trenton rocks are everywhere good Port 
land-cement materials, though in some places they will require pun 
limestone, and in other places clay, to bring them to proper composition i 
WESTERN PENNSYLVANIA. 
Two small Portland cement plants are in operation in wester] 
Pennsylvania, each of which presents certain features of interest. 
The Portland cement plant of the Clinton Iron and Steel Company 
located at Pittsburg, was the first plant to utilize a mixture of blast 
furnace slag and limestone in the manufacture of a true Portland 
cement, having commenced this industry several years before it wai 
taken up by the Illinois Steel Company at Chicago. 
The Crescent Portland Cement Company, located at Wampumn 
Lawrence County, is one of the oldest Portland cement plants in th | 
United States, having gone into operation when the Saylors were thiil 
only operators in the Lehigh district. The material used here is thl| 
Ferriferous (Vanport) limestone, of Carboniferous age, and a shal 
overlying this limestone. 
Analyses of Portland cement materials, Wampum, Pa. 
Silica (SiO t ) 
Alumina (A1 2 3 ) 
Iron oxide (Fe 2 3 ) .. 
Lime (CaO) 
Magnesia (MgO) 
Carbon dioxide (C0 2 ) 
Limestone. 
SI 
ale. 
5. 52 
65. S 1 
2.97 
{ 
2 1 . 5 ' 
G.Ci 
49.66 
A\ 
.78 
.H 
n.d. 
n. ( . 
PORTLAND-CEMENT RESOURCES OF RHODE ISLAND. 
The only limestone beds in this State large enough to be of economi 
importance occur on the Lime Rocks, two small islets lying between 
Newport and Fort Adams. The limestones occurring at this localit 
have been rather doubtfully referred to the Cambrian in the latest dis 
cussion" of Rhode Island geology. Though commonly referred to a 
« Foerste, A. F., Geology of the Narragansett Basin, Mon. U. S. Geol. Survey, vol. 33, i>. 318, 1899. 
