REPORT OF THE DIRECTOR I9IO III 



netite, which has, however, a very unequal distribution due to its 

 tendency to aggregate in bands and schlieren surrounded by rock 

 containing less than the average proportion of magnetite. 



The Gellivare iron ores occur in the form of lenses, bands and 

 chimneylike bodies with a linear arrangement that conforms more 

 or less closely to the secondary structures of the wall rocks. Three 

 or four parallel series of deposits can be recognized, the individual 

 members of which vary in magnitude and shape and also in their 

 characters. There is the same tendency toward overlapping which 

 is so pronounced in most of the Adirondack mines. Horses of 

 pegmatite and of the country rock are not infrequently encountered 

 in the midst of the ore, reminding one of the occurrences in the 

 " Old Bed " mines at Mineville and in the Lyon mountain deposits. 

 The similarity of the tw^o districts has been noted by Professor 

 Sjogren who visited Mineville in 1891.^ 



The ores themselves present some striking contrasts. The high 

 phosphorus ores are the same granular mixtures of magnetite and 

 apatite as are represented by the product of certain Adirondack 

 mines, but on the other hand the mixed magnetite and hematite ores 

 and the purer bodies of the latter in contact with, or independent 

 of, the magnetite are foreign to our State. This feature we found 

 to be repeated at Kiruna and in many of the central Sweden locali- 

 ties. The hematite is specular and not pseudomorphic after mag- 

 netite as is the case with the few occurrences of this mineral in the 

 Adirondacks. Here it is undoubtedly a result of catamorphic pro- 

 cesses in very limited areas in which the magnetites have been 

 intruded, faulted or otherwise exposed to accentuated weathering. 

 Professor Hogbom- refers to the possible secondary origin of the 

 hematite at Gellivare, stating that this derivation is suggested at 

 times by decomposition of the adjacent wall rocks; but he also 

 points out that the contacts cannot be distinguished in other cases 

 from the magnetite contacts. The relation of the two ores in this 

 district is thus open to question. With reference to Kiruna, Dr 

 Per Geijer^ expresses the view that the hematite, except where its 

 presence can be attributed to surface alteration, is an original con- 

 stituent of the ore bodies, though in that section it appears to occur 



1 The Geological Relations of the Scandinavian Iron Ores. Am. Inst. 

 Min. Eng. Trans. 1908, 38:794-95. 



2 The Gellivare Iron Mountain. Guide to Excursions of the Interna- 

 tional Geological Congress. 



3 Geology of the Kiruna District. Stockholm, 1910, p. 257. 



