584 



EDWARD SAMPSON 



The manganiferous portion of the chert from the same locality- 

 is seen in thin section to consist of a breccia of two sorts of chert. 

 The matrix is chert containing numerous minute cracks with filled 

 manganese oxides which give a dark color to the whole, and the 

 fragments are clear sihca whose margins appear to have been slightly- 

 stained with manganese. In these stained portions botryoidal 



Fig. 3. — From same field as Figure 2. Shows detail of banding and dust of iron 

 oxide included in clearer silica areas. Magnified 370 diameters. 



and spherical structures are seen, both showing a faint radial 

 arrangement of the constituent silica. In places in the clear silica 

 fragments manganese oxides fill small irregular cracks several of 

 which radiate from a common point and appear to indicate shrink- 

 age. 



Jasper from the interstices of the pillows on the first point 

 west from Deepwater Point of the Northwest Arm of Fortune 

 Harbor shows a structure very similar to that which is illustrated 

 in Figure 2, 



