38 Minnesota Academy of Science 



rence, and more or less associated with sulphides of lead and zinc. 

 In the upper levels the ore was considerably enriched, and probably 

 contained the higher grade copper sulphides. Occurring in stocks of 

 bluntly conical form with the point downward the interior struc- 

 ture of the ore bodies cannot now be studied. They consisted large- 

 ly of nearly pure pyrite with a slight percentage of copper. There 

 was also a quartzose mixture of copper pyrite and pyrite containing 

 angular fragments of quartzite and limestone. 



There is here also a considerable development of skarn at the 

 contact of quartzite and granulite. It consists of a dark green mass 

 of radiate amphibole sometimes garnetiferous. Then there are 

 skols more or less closely connected with the pyrite stocks and 

 surrounding them or separating them from the other rocks. The 

 skols consist partly of primary minerals, such as amphibole, biotite 

 and cordierite and partly of their hydrated derivatives, chlorite, talc 

 and falunite. There are also secondary garnets and magnetite octa- 

 hedrons and later sulphides. The skols sometimes have a thickness 

 of ten to fifteen meters, and again they thin out rapidly. They grow 

 smaller in depth and have in general a development proportional to 

 the extent of the ore mineralization. The richest ores the mine 

 ever produced came from the upper zones of the skols. 



The "hard ores," so-called, lie immediately in the quartzite 

 without being enclosed by skols or leaders, and pass by insensible 

 gradations into the rock itself. All the ores appear to come to an 

 end at the maximum depth of 250 to 280 meters. 



Gold occurs associated with galenobismuthite, in small quartz 

 veinlets. Some selenium has also been found associated with trap 

 dikes which contain amphibole in a felsitic ground mass of quartz 

 and plagioclase. The gold ore was richest at the depth of from 

 40 to 100 meters. Workable gold ores have not been found below 

 200 meters. 



The surface of the pyrite and neighboring limestone in some 

 places retains the grooving and striatums of the glacial period. It 

 is interesting to note that there has been barely perceptible oxida- 

 tion and solution in the five thousand or more years that have 

 elapsed since Jack Frost here made his mark. 



One of the memorable events of the trip was a luncheon held 

 deep underground in an old stope in the Falun mine. Lighted by a 

 thousand candles, and with a blazing fire in an old rise connected 

 with the surface, the table spreads dazzled us by their whiteness 

 against the dark rock background, and the glasses and silverware 

 sparkled with unusual brilliancy. Here in this immense chamber 

 had worked miners before the discovery of America. The marks of 

 their tools remain, and the place where the last pile of burning fag- 

 gots hollowed out the solid ore, or the face of the drift smooth and 

 rounded instead of rough and jagged as when made by explosives, 

 conveys a faint idea of the infinite slowness and labor with which 

 the work of mining was carried on. Here on the rocks are carved 

 the names of rulers and nobles long since passed away. Even the 

 room itself bears the name of "Algemeine Frieden", or Universal 

 Peace, given to it at a celebration after the battle of Waterloo. 



After luncheon speeches were in order and then a German mfn- 



