358 The Acton Copper Mines, 



copper ore of the conglomerate is related to the fragments, were 

 ascertained by slitting a slab of the rock by means of a lapidary's 

 wheel and polishing the surface. The same test has been applied 

 to a block of the Upton conglomerate, and it is found there is 

 some analogy in the two cases, except that the Upton ore is alto- 

 gether pyritous sulphuret and much more thinly distributed among 

 the fragments. While large blocks of the Acton conglomerate give 

 thirty per cent, and upwards, of pure metal, the best blocks obtain- 

 ed by me from the conglomerate of Upton do not yield more than 

 five per cent. But this if the quantity of rock with such a per 

 centage were larger and the masses not too widely scattered, would 

 constitute a valuable mine. It would, however, require a careful 

 crop trial to determine whether the quantity is available." 



Since these observations have been made by Sir William Logan, 

 the cupriferous deposits have been much more exposed, and their 

 character more distinctly marked. In order to bring the matter 

 fully befo)"e our readers we would further avail ourselves of certain 

 geological notes which we found in the hands of the proprietors 

 of the mines, and which we are kindly permitted to use, the 

 descriptions and conclusions of which, after careful inspection of 

 the ground, we are disposed to accept. 



1. A2o;pearances of Mr. Sleeper^ s Openings. 



Eastern Opening. — Beds dip N. 40"" W. about 50°, and 

 consist of nodular limestone alternatino- with shale and over- 

 laid by it. Copper Pyrites in small, apparently not workable, 

 quantity, occur in both rocks, especially at their junction. The 

 shale is much tinged with carbonate of copper. Underlying the 

 limestone is a hard gray, irregularly bedded, earthy rock ( ? a 

 volcanic ash or tufa). This rock I regard as allied to Palagonite 

 tuff, and for convenience shall call it simply tufa or tufaceous 

 rock. The section at this place is nearly as follows : (Fig. 1). 



(a) Shale, (h) Copper Limestone, (c) Tufaceous rock, (d) Limestone 

 of the hill or ridge south of the Mine. 



Second Opening (Fig. 2). — This is connected with the 

 former by a trench in the strike, showing shale with copper stains. 



