Trenioii Linustone of Minneapolis and St. Paul — Hall. Ill 



below this exposure the copper bearing rock may be regarded as a 

 dike. The copper is found in thin sheets and bauds in the mas- 

 sive rock. 



About tlieyear 1(S71) the Minnesota silver and copper miniug 

 company did soiie preliminary mining work on a vein running 

 across a small island off the south side of Pigeon Point. The vein 

 carried a belt of copper ore, mingled bornite and chalcopyrite with 

 a little silver which was penetrated by a shaft 50 feet deep. The 

 country rock is a gray quartzite generally regarded as of Animike 

 — Huronian — age. The general position of this formation along 

 the south side of Pigeon Point is east and west with a southerly 

 dip of 10 degrees to 15 degrees. Many barrels of ore were raised at 

 the time of opening the mine but so far as the writer knows no 

 systematic work has been prosecuted. Maj. T. M. Newson of St. 

 Paul, has, I believe been the leading spirit in this enterprise. 



The foregoing notes are the result of a recent attempt by« the 

 writer io discover the past results and a possible future of copper 

 mining in Minnesota. Many efforts have been made, and par- 

 ticularly in the Lake Superior Keweenawan region fi'om which the 

 results are too meagre and futile to be mentioned here. Strat- 

 igraphically the first work was done in the Cambrian rocks (Le 

 Sueurs' labors) but more recently investigations while largely car- 

 ried on in the Keweenawan, the true Cupriferous series, have to 

 some extent, been pursued down into the Huronian. 



Finally the results have been meagre and the impression of 

 the writer is that copper mining will never become a profitable 

 industry either in the southwestern extension of the Keweenawan 

 series around Chegwatonaor in the larger area to the north of Lake 

 Superior in Minnesota. 



October r>. JRS5. 



[Paper B:\ 



TWVl LITHOLOGICAL CHARACTERS OF THE TRKNTOX LIMESTONE OE 

 MIN^NEAPOLIS AXI) SAINT PAUL, WITH A NOTE NT THE BORiNGS 

 OF THE WEST HOTEL ARTESIAN WELE. C. W. Hall 



The Quarry Studied. — As a representative exposure of the 

 Trenton limestone of this vicinity, the quarry at the foot of ftth 

 avenue southeast was taken. From this quarry, rock has been 



