2'6 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 2 



The belt in which bementite is found is part of a densely forested 

 and extremely rugged area in which the local relief ranges from 2,000 

 to 6,000 feet or more. It has not been thoroughly prospected or 

 even explored in detail, though most of it is within 15 or 20 miles of 

 Puget Sound. From Hoodsport the deposits along the north and 

 south forks of Skokomish River can be reached over a fairly good road 

 and trails, but most other places in the belt are rather difficult of 

 access. 



The rocks of the bementite area are chiefly greenstone, arkosic 

 sandstone, argillite, and a deep red or maroon impure limestone that 

 forms discontinuous layers and lenses. These rocks are steeply tilted 

 and compressed and show the effects of regional metamorphism. The 

 strike appears to be generally northeastward parallel with the distribu- 

 tion of the deposits. The limestone contains poorly preserved fos- 

 sils of minute foraminifera determined by Dr. T. W. vStanton as most 

 probably belonging to the genus Glohigerina, which may indicate the 

 rock to be Mesozoic or younger. The field relations show only that 

 the rock group is older than the recognized Tertiary of the region. 



The deposits that contain the bementite are either inclosed by or 

 closely associated with the limestone. They are tabular or lens- 

 like bodies, commonly from 5 to 20 or 30 feet in thickness and to be 

 measured in their other dimensions by hundreds or thousands of feet. 

 Parts of them are a bright red jaspery-looking rock composed of fine- 

 grained quartz and hematite mixed in various proportions. Locally 

 this material grades into practically unmixed hematite. The remaining 

 and commonly the larger parts of the bodies are chiefly a dense very 

 finely crystalline rock that consists chiefly of bementite. No dense speci- 

 men was found in which the bementite was entirely unmixed with 

 other minerals, and the texture of the rock is so fine that a heavy- 

 solution separation, as described further on, was found necessary to 

 obtain material suitable for analysis. Much of the bementite rock, 

 however, contains but a relatively small amount of other minerals 

 and, therefore, its properties are essentially the same as those of the 

 selected material to be described. The microscope shows the prin- 

 cipal associated minerals to be quartz, rhodonite, and a carbonate 

 near calcite and manganiferous calcite {n = 1.660 to 1.705), these 

 minerals being intergrown with the bementite and also deposited in 

 veinlets that cut it. 



Locally the bementite rock is cut by veinlets, visible to the unaided 

 eye, that contain one or more of the minerals quartz, calcite, manga- 



