232 KEMP'S ORE DEPOSITS. 



that was over 500 feet wide and 1600 feet long. Numerous other 

 less extensive ore bodies also occur in the neighborhood, and very 

 many elsewhere in the mountains. They are all titaniferous, al- 

 though, as often happens with such ores, they are low in phosphorus 

 and sulphur and at times quite high in alumina. At present 

 they are not utilized, but it is to be hoped that in time processes 

 will be developed to treat them. Fairly high titaniferous ores oc- 

 <jur in New Jersey on Schooley's Mountain and to the southwest, 

 and small amounts, say up to \% of TiO 2 , are known in many 

 others. 1 The wall rock of these ores should receive microscopic 

 examination to determine if it affords a mineralogical parallel with 

 those of the Adiroridacks. 



Titaniferous ores are also known in Virginia and North Caro- 

 lina, 2 in the gabbros of Minnesota, in Wyoming, in Colorado the 

 last three of which have already been mentioned in the text. 

 Microscopic determinations of the wall rock, where not already 

 made, would be of great interest. Their geological relations have 

 long been known in Sweden and Norway, but an igneous form of 

 origin has been but recently advocated. (Cf. p. 56.) 



Page 130. In the review of the methods of formation of mag- 

 netite-lenses, the method by segregation or as segregated veins 

 was omitted. As it is viewed with favor by many reliable observ- 

 ers, it should have its place. By this method the iron oxide is con- 

 ceived to concentrate from a state of dissemination in the walls by 

 slow secretion in solution, to form the ore bodies along certain favor- 

 able beds. The action is regarded as analogous to the formation 

 of concretions, and is illustrated on a small scale by the well-known 

 disks of pyrite and calcite that form in clays and shales. It is a 

 curious fact, however, that some magnetites are in wall rock that 

 hardly shows a trace of even a dark silicate. Thus the lenses at 

 Hammondville, in the Lake Champlain district, are in a pure, white 

 gneiss that only has a little garnet near the ore, but it is possible 

 that elsewhere the explanation may be the most reasonable one. 

 Where it applies we would expect hornblende and other ferru- 

 ginous minerals in the walls. 



1 B. F. Fackenthal, " Titaniferous Ores in the Blast Furnace," Trans. 

 Amer. Inst. Min. Eng., February, 1892. R. W. Raymond, Ibid. 



2 H. B. C. Nitze, "Notes on some of the Magnetites of Southwest 

 Virginia and the Contiguous Territory of North Carolina,*' Trans. Amer. 

 Inst. Min. Eng., June, 1891. Reprint p. 13. See also discussion of the 

 paper at the same meeting. 



