ECKEL.] 
WASHINGTON. 
PORTLAND CEMENT INDUSTRY IN VIRGINIA. 
323 
One plant is in operation in Virginia, that of the Virginia Portland 
Cement Company, at Craigsville. The materials used are limestones 
and shales of Lewistown (lower Helderberg) age. Analyses of these 
materials follow, quoted from the Cement Industry. 
Analyses of cement materials used at Craigsville, Va. 
Silica (Si0 2 ) 
Alumina ( Al,() 3 ) 
Iron Oxide (Fe 2 3 ). . 
Lin.e(CaO) 
Magnesia (MgO) 
Carbon dioxide (C0 2 ) 
Water 
Lime 
stone. 
11. d. 
1 n. d. 
54. 30 
.66 
4:;. 63 
Shale. 
53.63 
24. 47 
5. 94 
1. 79 
10. 03 
PORTLAND-CEMEKT RESOURCES OF WASHINGTON 
The geology of the State of Washington is not sufficiently well 
known to permit a very detailed statement regarding its cement 
resources. It must therefore be borne in mind that deposits of lime- 
stone available for Portland-cement manufacture, in addition to those 
discussed below, may exist in parts of the State which have not been 
carefully surveyed. 
Limestones are known to occur in large quantity in two widely 
separated areas in Washington, and it is from these two areas that the 
■[State's principal supplies of limestone (and marble) for building, lime 
burning, and cement are now being obtained. The two areas are: (t) 
The San Juan Islands in northwestern Washington and (2) Stevens 
"'County in northeastern Washington. 
SAN JUAN ISLANDS. 
Large limestone deposits, probably of Cretaceous age, occur on 
various islands of the San Juan group, in the Strait of Juan de Fuca. 
These limestone beds are surrounded by igneous rocks, by which the 
limestones have been metamorphosed, occurring in consequence in 
the form of crystalline limestone or marble. 
The limestone deposits on these islands vary greatly in size. The 
largest bed known is that of the Roche Harbor Lime Works, on San 
Juan Island. This extends a all the way across the peninsula from 
"Ann. Rept. Wtftshingon Cool. Survey for 1901, pt. 3, p. 25. 
