324 CEMENT MATERIALS AND INDUSTRY. [bull. 243. 
Roche Harbor to Westcott Bay, a distance of halt' a mile. The width 
of the belt, as exposed at the outcrop, is 850 feet, and its average thick- 
ness above water level is 250 feet. This deposit is now extensively 
worked, the product being used both for lime burning and for smelter 
flux. An analysis a of the limestone gave the following result: 
A nali/six of limestone, Roche Harbor Lime Works quarry. 
Silica (Si0 2 ) 0. 25 
Alumina (A1 2 3 ) | 
Iron oxide (Fe 2 3 ) J ' 8 ° 
Lime carbonate (CaC0 3 ) 98. 85 
Other smaller deposits of limestone occur on various islands of the 
San Juan group. One of these deposits, located on the west coast of 
San Juan Island, about 7^ miles from Friday Harbor, now supplies > 
material for a 2-kiln lime plant. On Orcas Island, near East Sound 
and Deer Harbor, similar deposits exist, and several are being worked,!, 
the product being burned into lime by two 1-kiln lime plants. 
NORTHEASTERN WASHINGTON. 
The Okanogan Highlands of northeastern Washington are largely 
made up of a series of crystalline rocks, most of which are of unknow^i 
age and origin. At various points in this crystalline area, particularly 
in portions of Stevens County, deposits of crystalline limestone or<r 
marble occur. The age of these limestones is not certainly known!, 
but it is supposed that they are, in part at least, Carboniferous. 
A number of these deposits have boon worked as marble quarries,- 
and a considerable amount of beautiful material is annually obtained, 
from them. The deposits are of equal, or perhaps even of greater, 
value as sources of Portland-cement material, for rocks that are too< 
much jointed and seamed to furnish decorative stone, or are of unsat- 
isfactory color, will be available for cement plants. 
Some of these rocks carry a high percentage of magnesium car- 
bonate or else contain a large proportion of various silicate minerals. 
These are, of course, worthless as cement materials. A large propor- 
tion of them are, however, very low in magnesia, and can be consid- 
ered available for Portland-cement material. A few of thorn, accord- 
ing to reports, carry a large percentage of argillaceous matter, thus 
approaching in composition the Lehigh "cement rock" of Pennsyl-i 
vania and New Jersey. 
a Ann. Rept. Washington Geol. Survey for 1901, pt. 3, p. 25. 
