The Acton Copjjei' Mines, 359 



Beginning at tbe great hill limestone, we have 22 paces without 

 section, then 27 paces shale and tufa, the latter predominatino- iu 

 the upper part, then 4 yards limestone, nearly vertical, then shale 

 ■extending about 30 paces. At the junction of the limestone and 

 upper shale are traces of copper pyrites, and black oxide of 

 copper. Section as follows : — the letters referring to the same 

 rocks as in Fig. 1. 



Third Opening {Sleeper''s latest). — At this place there is a great 

 thickness of vertical and contorted shale, apparently underlaid by 

 tufa. The copper limestone is represented by a layer of highly 

 cupriferous material about one foot thick at the outcrop. This 

 was only imperfectly exposed : (Fig. 3). The ore here is purple 

 copper. 



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Fig. 3. 



Fourth Opening i^Sleeperh shaft pit). — At this place the 

 copper limestone is highly developed, and presents an upper bed 

 about 5 feet thick, holding yellow pyrites and rapidly thinning out 

 toward the dip, a lower layer about 4 feet, very rich in purple 

 copper in laminai parallel to the bedding, and below this unproduc- 

 tive limestone and shale, which last also overlies the upper lime- 

 stone. The whole of these beds are thrown into a sharp anticli- 

 nal fold. The shaft has been sunk on the part dipping toward the 

 hill, say S. E., and the main pit exposes the crown of the arch 

 and its N. W. side. At the corner of the fold is a fissure or vein 

 running S. 20° W., underlying to the N. W., and containing 

 calc spar and quartz with yellow pyrites. The valuable portion of 

 the ore is, however, the 4 feet bed of cupriferous limestone. This 

 does not appear to run out so far as yet followed to the dip, but dis- 

 appears suddenly when followed to the east, where either a change 

 in the original deposition or a dislocation brings in a mass of the 



