no NEW YORK STATE MUSEUM 



upon the amount that can be exported ; in the case of the Kiruna 

 mines this is fixed substantially at 3,000,000 tons and for the Gelli- 

 vare mines at about 800,000 tons annually during a period of 25 

 years. It is believed, however, that these amounts will be in- 

 creased before long, as the magnitude of the resources becomes 

 better appreciated. The possibility that the ores may be needed 

 for iron manufacture in Sweden arises from the large water powers 

 of the country and their future application to electro-metallurgy. 



Turning now to the geological features of the magnetites, the 

 Lapland deposits will be first considered for the reason that they 

 have been on the whole less influenced by metamorphism, there- 

 fore are more readily interpreted, and their associations perhaps 

 more nearly approach those found in some localities of our own 

 State. Attention can be given only to the Kiruna and Gellivare 

 mines since the limited time of the excursion did not permit any 

 visits to the localities remote from the railroad. 



Rocks of syenitic composition are the prevailing ones associated 

 with the magnetites of Lapland. They range from massive, even- 

 textured or porphyritic, clearly igneous types to gneissoid and finely 

 granular phases that have entirely lost their igneous structures. 

 Quartz is a variable component. Magnetite, diopside, hornblende 

 and biotite are the chief dark constituents. Areas of granite and 

 gabbro interrupt the syenites, and the latter are penetrated by dike 

 intrusions of pegmatite, granite and more basic rocks. 



At Gellivare we saw the syenite in its varied development from 

 massive to extremely granulated and gneissoid types. With the ex- 

 ception of local granite intrusions and certain small belts of a basic 

 schistose rock that are considered by Professor Hogbom to repre- 

 sent igneous dikes, the syenite prevails throughout the ore-bearing 

 districts. No sedimentary gneisses are recognized in the vicinity. 

 The general impression gained from the cursory field study and 

 later comparison of the country rocks indicates close resemblance 

 to the ore-bearing syenitic gneisses in the northern Adirondacks, 

 particularly Lyon mountain, Palmer hill and Arnold, The main 

 element of difference that can be readily pointed out is that in the 

 Adirondacks the gneiss belts are seldom without some interfolded 

 remnants of the Grenville sedimentary rocks. Mineralogically and 

 chemically the two series are very similar. Both are characterized 

 by high soda percentages, which place them in the soda-syenite 

 class, the prevalence of perthitic and acid plagioclase feldspars, and 

 by relatively large amounts of free iron oxid in the form of mag- 



