COLLECTIONS IN ECONOMLC GEOLOGY AND METALLURGY. 81 



but ouly a small portion of this distance was sufficiently rich to be 

 mined. To illustrate this conglomerate six specimens are sliown : 



(1) Trap rock, found in patches overJyiugthe couglomerate. (5484L) 



(2) Couglomerate, carryiiig a little free copper, 200 leeE down iiiidino shaft. 

 (54854.) 



(3) Conglomerate, carrying a little free copper somewhat oxidized, '^iiO feet down 

 incline shaft. (54855.) 



(4) Red conglomerate, carrying a little free copper. (5484G.) 



(5) Epidote rock, carrying considerable free copper, somewhat oxidized on the sur- 

 face. (54845.) 



(G) Epidote rock, barren. (548o'3.) 



To represent the vein at diflerent depths and also cross-sections of 

 the vein, the following specimens are shown. From No. 2 shaft: 



(1) Vein rock, consisting essentially of quartz and epidote, carrying some free 

 copper. Kepresents the vein along the hanging wall at the 22d level, south of the 

 shaft. (5485().) 



(2) Vein rock, barren, represents the vein for about 100 feet on the 22d level south 

 of the shaft. (54857. ) 



(:?) Trap rock, from hanging wall at 24th level, south of shaft. (54842.) 

 (4) Trap rock, from bottom of the shaft, 60 feet below 24th level. (54801.) 



From No. 4 shaft : 



(1) Trap rock, from hanging wall at 25th level. (54840.) 



(2) Parting between the hanging wall and vein at 25th level. (54839.) 



(3) Vein rock, consisting essentially of epidote and quartz with some calcite car- 

 rying a little free copper. Vein 20 inches wide. From 25th level. (54838.) 



(4) Trap rock, from foot wall at 25th level. (54841.) 



(5) Vein rock, consisting essentially of epidote and quartz with considerable free 

 copper. From 24th level south of shaft. (54843.) 



- (6) Trap rock, from hanging wall at south end of 24th level. (.54858.) 



THE OSCEOLA MINE. 



The Osceola mine was selected to illustrate the amygdaloid mines. 

 It is situated in Houghton County, Michigan, and work was commenced 

 upon it in 1873. The first work done was upon the conglomerate bed, 

 worked by the Calumet and Hecla Company on an adjoining lot, but 

 the bed was fouud to be poorer than in the Calumet and llecla ground, 

 and was soon abandoned as unprofitable. In 1877 work was com- 

 menced upon an amygdaloid bed 750 feet southeast of the conglom- 

 erate, which had been found to be copper bearing, and has been con- 

 tinued until it lias been developed into a very successful mine. 



The mine is not upon a true v^ein, but is simply upon the cupriferous 

 portion of one of the members of tlie regular rock series. The outline 

 of the deposit is very irregular, the original surface of the rock was 

 wavy and uncertain, and that portion of the rock nearest the surface 

 being open and porous, was much more favorable for the deposit of cop- 

 per. The depth to which sufficient copper to pay for working was 

 deposited varies greatly, while occasionally the copper penetrates the 

 overhanging rock or hanging wall. These conditions of deposition 

 give undulating surfaces to both sides of the deposit, and while the bed 

 9U0— No. 4L' 6 



