It is interesting to compare the views of a prominent 

 American engineer, Courtenay De Kalb, who, in an article 

 published in the Engineering and Mining Journal in June„ 

 1888, dealt with their occurrence and probable influence upon 

 the deposition of cassiterite in the Appalachians in Western 

 North Carolina. "The paragenesis of cassiterite in the 

 Appalachians is such as to induce strong suspicions," he re- 

 marks, "that it may be found in workable deposits some- 

 where in the chain. I have heard of no case of its occurrence 

 in greison or in the granite series of the region, but always 

 in quartz veins in close proximity to basaltic dykes. The 

 quartz, which is invariably full of cavities is strongly im- 

 pregnated with mispickel, and has associated with it topaz, 

 apatite and sometimes considerable amounts of fluor-spar. 

 The occurrence of minerals containing fluorine in the neigh- 

 borhood of trap dikes is an indication of the probable exis- 

 tence of tin in the same locality * * * * This association of 

 tin bearing rocks with basalt finds an explanation in the dis- 

 covery of Daubree that fluoride of tin is volatJ_le at a high 

 heat, but is readily decomposed in contact with other sub- 

 stances, resulting in the formation of other fluorides, while 

 stannic oxide is set free. An eruption of basaltic lava would 

 provide all the conditions for the volatization and escape of 

 fluoride of tin, and for the deposition of cassiterite in flssures 

 nearer the surface. Of course, this applies only to tin ore in 

 true veins, but in the Appalachians, where this is the prevail- 

 ing condition, a knowledge of this relationship may be help- 

 ful in leading to important discoveries." 



Remembering that the Kennebec Valley lies in the re- 

 gion of the northern Appalachians and that all the geologic 

 conditions and mineral occurrences mentioned by Mr. De 

 Kalb are in evidence at Winslow, one may be pardoned for 

 accepting his conclusions. 



Before leaving the subject of the chemistry of tin depo- 

 sition, it will be of value to compare the well-founded theo- 

 ries of the great French scientist, Daubree as so briefly out 

 lined by De Kalb, with those of an eminent English geologist, 

 Donald A. MacAlister, Esquire, P. G. S., who in a paper on 

 "Tin and Tourmaline" read before the Geological Society of 

 London in 1903, remarked: 



"Cassiterite hardly ever occurs without tourmaline, al- 

 though the latter is found without the former; Tience it ap- 

 pears that tourmaline-producing constituents and influences 

 are of wider range than are those of cassiterite. Boron triox- 

 ide is an extremely common accompaniment of volcanic ac- 

 tion and there can be no doubt that it has acted powerfully 



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