IRON ORES 



351 



Mtn., about 100 feet above Lake Champlain, and show very 

 considerable excavations, which are practically dry, as the situation 

 for mining is very convenient. The ore is 10' thick, strikes 

 K. 70-S0° E. and dips 50° south. Gabbro forms the walls right 

 up to the ore on both sides. It is the metamorphosed variety 

 with the copious reaction runs of garnets. The writer was told 

 that there is another opening to the south. There is a separator 

 on a level with the lake, and above the mines, in a terrace in a 

 break in the hills, are the old boarding houses. From this terrace 

 there is a most superb view of the lake and the Green Mountains. 

 The mine is just across from Fort Cassin. The analysis of the ores 

 given in the opening table shows that they contain from 13-16 TiO^ 

 with 32.5 to 44.7 Fe. 



GENERAL REMARKS 



There seems little if any prospect of profitable mines in TTest- 

 port in the future. Those ores that are reasonably near the lake 

 are certainly titaniferous and cannot be used under the present cal- 

 culation of blast furnace slags and mixtures. The non-titaniferous 

 ores which may be in the western limits of the town, are extremely 

 inaccessible if indeed in any quantity. 



In their scientific relations the titaniferous ores are of great inter- 

 est. They invariably occur in dark, basic gabbros and in such rela- 

 tions as to make the inference unavoidable, that they are excessively 

 ferruginous or basic, portions of the original igneous magma. There 

 is no sharp line of demarcation between ore and wall but a gradual 

 passage of one into the other, although in a short space. We are 

 coming to recognize titaniferous magnetites in these relations in 

 many parts of the world, and "Wadsworth* in this country, 

 Derby f in Brazil, and Yogt^: in Sweden have already called atten- 

 tion to such. 



*M. E. Wadsworth. The Iron Ore or Peridotite of Mine Hill, Cumberland, R. 

 I. Bull. Min. Comp. Zool. 1880. VII. 



fO. A. Derby. Magnetite Ore Districts of Jacupiranga and Ipanema. Sao 

 Paulo, Brazil. Amer. Jour. Sci., April, 1891. 311. 



X J. H. L. Vogt. Bildung von Erzlagerstatten durch Differentiations-processe in 

 basischen Eruptivmagmnta; Zeitschrift fur praktische Geologie, I. pp 4, 125, 257. 

 This paper appears in its completest and latest form in the reference given, 

 although the conclusions had been previously published elsewhere. 



