120 
CEMENT MATERIALS AND INDUSTRY. 
[BULL. 243 
of igneous rock, which locally interfere with quarrying. If the projected branch 
railroad up Pit Riveris ever built, it would pass near this great limestone. 
A third belt of limestone occurs near Kennett, within a few miles of the railroad; 
and furnishes not only flux for the Mountain Copper Company at the Keswicl 
smelter, but also lime, which is burned at Kennett and shipped to many points m 
the Southern Pacific Railroad. This limestone is of Devonian age and consequentlj 
much older than the others. Although the limestone is not nearly as large as til 
others and isolated on ridge crests by igneous rocks, it is more valuable becail 
more accessible. Smaller masses occur near Horsetown and at several points on tl 
plain northeast of Buckeye, where lime has been burned, but since the Kennel 
locality has been opened they are of little importance. 
Below are given partial analyses of three of the limestones abo™ 
described by Mr. Diller: f 
Analysis of limestone from Redding district, California. 
Silica (Si0 2 ) 
Alumina (A1 2 3 ) . . 
Iron oxide (Fe 2 3 ) 
Lime (CaO) 
Magnesia (MgO) .. 
2.0 
1.5 
52.5 
n. d. 
4.0 
1.5 
51.0 
n. d. 
.'{ 
4 
n. | 
53 
1. Near U. S. Fishery at Baird. Bull. U. S. Geol. Survey No. 225, p. 176. 
2. Brocks Mountain, 6 miles northeast Delamar. Ibid. 
3. Kennett. Eighth Ann. Rept. California State Mineralogist, p. 572. 
PORTLAND-CEMENT INDUSTRY IN CALIFORNIA. 
Until within the past two years only one Portland-cement plant haflii 
succeeded in establishing itself in California. This was the Calif or™ 
Portland Cement Company, with works located at Colton, in souther 
California. During 1903, however, two additional plants went int 
operation, both located near San Francisco. In consequence of thijag 
slight development of a local industry, California has been supplie 
largely with foreign Portlands, alwa}^s high-priced and frequently ( ] 
poor quality. 
The plant of the Pacific Portland Cement Company is located aboi 
6 miles east of Suisun, Solano County. The materials used are tra^ 
ertine — a very pure lime carbonate deposited from waters carrying 
in solution — and clay.. Eight rotary kilns are in operation, Baker 
field oil being used for fuel. The electric power necessary for runnir 
the plant is derived from Marysville. Analyses of the raw materia 
and of the finished cement, which is marketed as "Golden Gate 
brand, follow: 
