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



extent that its removal by the use of a magnet may not have been 

 complete. 



The mechanical inclusion of the ore would necessarily lessen or lower 

 the percentage of the other constituents. 



The analyses of the serpentine, in which the asbestos is included, 

 require brief consideration. To this series is also added the theoretical 

 composition of serpentine as given by Professor Kemp in his " Hand- 

 book of Rocks," and two analyses of the amphibolite which forms the 

 crest of Belvidere mountain. 



Number Si0 2 A1 2 3 Fe 2 3 FeO MgO CaO H 2 Total 



1 44.14 42.97 .... 12.89 100.00 



90 40.21 5.73 .... 40.98 0.82 12.68 100.42 



35 40.82 7.63 .... 38.40 1.37 12.41 100.63 



5 42.93 32.77 .'... 5.96 14.29 1.76 97.71 



23 44.36 28.85 .... 8.74 11.70 1.71 95.36 



Number 1. Theoretical composition of serpentine. Kemp's Handbook of Rocks, 

 page 140. 



Number 90. Analysis of serpentine from foot of the serpentine slope, Belvidere 

 mountain. 



Number 35. Analysis of serpentine from the upper slope and taken from the 

 property of the United States company. 



Number 5. Analysis of amphibolite from the base of the formation C0 2 . 



Number 23. Analysis of amphibolite from the top of Belvidere present but not 

 determined. It accounts for the low total. 



An inspection of the analyses of the serpentine, when considered in 

 the light of the theoretical composition, brings to light some variations 

 needing a word of explanation. It' will be seen that the silica runs 

 noticeably below the theoretical limit, and in fact below that usually 

 found in many serpentines derived from pyroxene or olivine rocks. 

 This can be accounted for by the fact that the rock almost invariably 

 shows a large amount of iron ore, and probably by far the greater part 

 of the total estimate of the alumina and iron is composed of iron oxide. 

 This, as in the case of the fiber, would lessen the relative amount of 

 silica in the analysis. 



The presence of a small amount of alumina is to be accounted for as 

 well. It is already a recognized fact that alumina cannot be considered 

 as an introduced product, but, to the contrary, must have formed a part 

 of the original rock from which the serpentine was derived. Now, the 

 facts gathered from the thin-sections suggest as the original a rock 

 containing an orthorhombic pyroxene. The very large amount of 

 magnetite precludes a derivation of the pyroxene by metamorphism 

 of limestones or highly calcareous deposits. If this interpretation be 



