96 BULLETJN 42, UNITED STATES NATIONAL MUSEUM. 



lu the stope about 50 feet below the seventh level these two cuprifer- 

 ous layers have uuited, forming a layer of very rich ground, beginning 

 3 feet from the foot wall and being 5 feet in width : 



(1) Conglomerate, coutaining much free copper and coasiderable calcite. (54652.) 



(2) Conglomerate, compact and barren. (54699.) 



(:?) Conglomerate, showing intersection of a calcite vein and a slip. (54695.) 



The following specimens, although not taken at one point, represent 

 a characteristic section of the bed : 



(1) Trap rock, from the greenstone range, between 500 and 600 feet thick at this 

 point. (54684.) 



(2) Free copper, from the contact between the trap and the conglomerate. (.54741.) 



(3) Free copper, from the contact, has been flattened out by pressure. (54737.) 



(4) Free copper, from the contact, has been flattened out by pressure. (54738.) 



(5) Conglomerate, with pebbles varying very much in size. Found only within 6 

 or 7 feet of the top of the conglomerate. (54667.) 



(6) Amygdaloid, from a boulder near the foot wall. (54692). 



(7) Free copper, cast of a peculiar shaped amygdaloid pebble ; from near the foot 

 wall. (547.32.) 



(8) Free copper, cast of a large flat pebble. (54735.) 



(9) Free copper, apparently the cast of several pebbles that touched each other; 

 from near the foot wall. (547:i6.) 



(10) Free copper, apparently the beginning of the cast of a pebble, showing the 

 crystalline interior; from near the foot wall. (54691.) 



(11) Free copper, cast of a pebble, with adhering conglomerate ; from near the foot 

 wall. (54739.) 



(12) Amygdaloid, much decomposed, aud containing free copper; from near the 

 foot wall. (54723.) 



The Delaware stamp mill. — The treatment in the mill is nearly the 

 same as at the Osceola mill. To illustrate the extraction of copper in 

 the mill sixteen specimens are shown : 



(1) Conglomerate, containing free copper. Represents the average of the material 

 sent to the mill. (54744.) 



(2) Crushed rock, as it passes the sieves of the mortar. (54712.) 



(3) Heads, from mortar ; consisting of copper in pieces too large to pass the sieves. 

 TLo silver in the copper is generally found in this material; it is picked out by hand 

 and averages about 16 pounds a month. Grade No. 1, nearly pure copper. (.54706.) 



(4) First-class material, from the first division of the hydraulic separators. (54719.) 



(5) Second-class material, from the second division of the hydraulic separators. 

 (54718.) 



(6) Third-class material, from the third division of .the hydraulic separators. (54721.) 



(7) Fourth-class material, from the fourth division of the hydraulic separators. 

 (54715.) 



(8) Copper, separated on the roughiug sieves. Grade No. 2, containing about 95 

 per cent, of copper. (54707.) 



(9) Coarse tails, from the roughing sieves. (54720.) 



(10) Fine tails, from the roughing sieves. (54714.) 



(11) Copper, separated on the tiuishing sieves, including the coarse material in the 

 sieves aud the line hutchwork that has passed through. Grade No. 3, containing 

 about 86 per cent, of copper. (54708.) 



(12) Coarse tails, from finishing sieves. (54717.) 



(13) Fine tails, from finishing sieves. (54713.) 



(14) Copper, separated from the slimes by treating them on the Evans slime tables 



