Februaey 28, 1908] 



SCIENCE 



349 



fluorine and barium. Fluorine is present in 

 considerable amount. Near these springs the 

 foot-hills of pre-Cambrian gneiss contain vein- 

 lets of colorless fluorite, which doubtless was 

 deposited by these hot waters when they issued 

 at a somewhat higher elevation. Still higher 

 up on the western slope is found a narrow 

 vein, which contains small amounts of gold 

 and silver in a gangue of colorless fluorite 

 with a little barite, and this vein appears to 

 be capped by a deposit of tuffaceous character, 

 which principally consists of carbonate of 

 lime, but also contains a notable amount of 

 fluorine and traces of gold and silver. It is 

 believed that this vein and the deposit were 

 formed at about the same time, the deposition 

 of the lime carbonate taking place at the sur- 

 face while fluorite was the principal deposit 

 in the vein a short distance below the surface. 

 All this indicates that these springs have been 

 active during a long time, and it is probable 

 that the hot waters issued at gradually lessened 

 elevations as the erosion deepened the valley. 



At the 197th meeting of the society, held 

 on December 19, 1907, Mr. Waldemar Lind- 

 gren, the retiring president, presented an ad- 

 dress, entitled " Present Tendencies in the 

 Study of Ore Deposits." 



Mr. Lindgren stated that he wished to place 

 before the society in the briefest way the 

 tendencies of the study of ore deposits as 

 shown during the first seven years of the 

 twentieth century. In a way the year 1900 

 might be considered as marking a mile-stone 

 in the progress, for during that year the pre- 

 vailing theories found specially clear exposi- 

 tion at the hands of many observers. The 

 activity of the various nations in this study 

 was mentioned, and it was shown that the 

 United States, Germany and Scandinavia 

 were most prominent in this respect. The 

 difl'erent modes of publication, monographic 

 descriptions versus geographic treatment were 

 emphasized. Next, the progTess in the tech- 

 nical methods was noted and special refer- 

 ence made to the metallographic methods to 

 the study of opaque minerals. The relation 

 of chemistiy to the science of ore deposits oc- 

 cupied attention and it was shown that in 



spite of some recent activity much remained 

 to be done in this direction, not only with 

 reference to investigation of methods of 

 mineral formation, but also, for instance, in 

 regard to the examination of the hot springs 

 and their deposits, especially in the western 

 states. The relative merits of the mono- 

 graphic and the geogTaphic treatment of ore 

 deposits was discussed. It was stated that ex- 

 cellent results had been obtained by Professor 

 DeLaunay in Paris by applying this method to 

 the ore deposits of Africa and Italy; it was 

 also shown that much remained to be done 

 in this direction in the United States. 



In regard to classification it was shown that 

 no consistent genetic system had as yet been 

 successfully applied. The usefulness of the 

 terms " syngenetic " and " epigenetic " was in- 

 sisted upon and mention was made of the 

 present tendencies in transferring a large 

 number of deposits to the epigenetic class. 

 This was exemplified by reference to iron ores 

 of Sweden and pyritic deposits in various 

 countries. In the latter class a syngenetic 

 origin was maintained by a few observers, but 

 the general trend of opinion was away from 

 the view of chemical precipitation in lakes or 

 seas and in favor of the subsequent introduc- 

 tion of the metals by hot solutions. 



Historic geology has its counterpart in our 

 branch of the science, and it was pointed out 

 that during the last years, both abroad and in 

 the United States, attempts have been made to 

 distinguish the various periods of mineraliz- 

 ing activity. 



The latter part of the address was devoted 

 to the question of the origin and genesis of 

 ore deposits, always a most difiicult and un- 

 satisfactory problem since its solution must 

 always be based on hypothesis and supposi- 

 tions. The general prevalence in the end of 

 the last century of the theory of ore deposi- 

 tion by circulating surface waters was noted, 

 and it was shown that the theory of ore de- 

 position from magmatic waters began to find 

 general acceptance in the first years of this 

 century. It is impossible to peruse the litera- 

 ture of any country of the last few years 

 without noticing the remarkable spread of this 

 idea. It seems to pervade the whole atmos- 



