428 V. F. MARSTERS — ASBESTOS DEPOSITS OF BELVIDERE MOUNTAIN 



along the line of movement. It would thus seem that the fibrous con- 

 tent, inasmuch as it fills cracks and seams, even of microscopic size, must 

 be secondary in origin. The stretching of the so-called fiber is due to 

 subsequent slipping after the deposition of the mineral within the orig- 

 inal fracture. The same conditions obtain at various points. It is very 

 well shown in the prospects of the United States company (Blake prop- 

 erty) 250 feet below the mill of the New England company, as well as 

 in many of the openings made by Tucker, Stone, and Farington along 

 the lower edge of the serpentine deposit. Occasionally on the fresh 

 fractures minute lamellar structure may be seen. Under the hand lens 

 they appear to be small silvery to light-green scales, but too small for 

 specific determination. On the basis of structure it is reasonable to con- 

 clude that these minute individuals may be some form of the lamellar 

 serpentine, to which the name Antigorite has been applied. It is to be 

 regretted that sufficient material is not at hand to determine this point. 



In the Tucker prospects, however, considerable variation in color and 

 an appreciable range in texture is noticeable. The color varies from 

 light grayish green to oily dark green, and brilliant dark green when 

 wet. Scattered through the mass are many patches of magnetite, with 

 which is associated a very small amount of chromite. It is in the Tucker 

 quarry that the best showing of cross -fiber in this serpentine area can 

 be seen. The dark bands of serpentine are intimately associated with the 

 fiber- bearing veins. They form the adjacent walls, and vary in width 

 with the size of the vein from one to several inches. When the veins 

 form a minute network the whole mass may assume the dark oil green 

 color and then form large bands and blotches 2 or 3 feet in diameter. 

 This peculiar association, so far as observed, is confined to the prospects 

 of the Tucker property. 



Local talc lenses. — The main part of the serpentine deposit is a fine 

 grained light grayish green rock, sometimes exhibiting a tendency to 

 become talcose, and wherever this occurs it is accompanied with a slight 

 schistose structure. In fact, on the line of the cross section, at a point 

 about 150 feet below the edge of the plateau, a number of talc-bearing 

 lenses may be seen. They contain moderately pure talc in the centers, 

 but grade out into the normal serpentine on either side with loss of the 

 schistose structure. From an economic point of view, they are too 

 small to invite any investigation. 



Structure of the Region 



The structure of the region is indicated in the accompanying cross- 

 section. Amphibolites form the upper 1,000 feet of Belvidere, and 



