1862.] HODGSON T7LVERSTON. 27 



miners, one of them being the principal person engaged, that " Pinel " 

 came next to the limestone in the drift. 



It would seem from fig. 2 that the deposit in the vertical shaft 

 (or rather the cavity in it) and that in the drift are not connected, 

 unless it be by a mere channel of communication, and even that must 

 remain only a matter of conjecture. The material called " Pinel," I 

 am told, does not form regular beds. 



The absence of bluish clay in the drift (see fig. 2) would lead to 

 the belief that the first waters had not penetrated this cavity. 



So far as I can learn, the material termed " Black Muck " was not 

 present either in the shaft or drift *. 



The accompanying section (fig. 2) of the last three shafts of the 

 Water-way will, I hope, throw much light upon the ground in ques- 

 tion. It has been drawn from information obtained, in writing, from 

 two of the chief men employed in the work, neither of whom have 

 been informed of my views on the subject. 



It seems to me that there is a steep precipice (or escarpment) in- 

 dicated by the abrupt germination of the rock in the Water-way 

 south of the No. 11 shaft, and that, from this point to below No. 10, 

 there may have been disturbance and continued change. 



Referring to the section of the shaft, fig. 2 of Mr. Bolton's paper 



* The following description of the material called " Black Muck" has been 

 obligingly given to me by Mr. Cameron, F.C.S. : — 



" ' Black Muck ' is a dark -brown substance found in the vicinity of hasmatite- 

 deposits, and is a very good indication of the neighbourhood of the oxides of iron 

 and manganese. It is never found of a uniform composition, but consists of 

 varying proportions of siliceous and aluminous materials, and of the oxide of 

 iron (hasmatite) and peroxide of manganese. The hasinatite iron-ores con- 

 tain generally a certain proportion of the peroxide of manganese, sometimes 

 titanic acid, and various other substances. When the haematite-ores are found 

 in irregular pockets, the ' Black Muck ' is very often found surrounding the 

 ore entirely, like an outward shell, which peels off from the surface of the iron- 

 ore, leaving it perfectly clean and glossy. When the ores are found in regular 

 strata, the ' Black Muck ' seems to assume a regular form also ; for it is then 

 almost always found overlying the vein of ore, running in the same direction, 

 and taking the same dip with varying thickness. Sometimes it is found under 

 the ore-deposit ; and is always a certain indication, when found, of the proximity 

 of the ores of iron and manganese. This substance, ' Black Muck,' is only found 

 in connexion with the hsematite-ores of iron ; and its general constituents may 

 be inferred from the composition of the following examples : — 



' Black Muck.' 

 No. 1. 



Oxide of iron (with a little alumina) 67*00 



Peroxide of manganese 5*00 



Siliceous matter 27*50 



99-50 



No. 2. 



Oxide of iron and alumina 28-00 



Peroxide of manganese 17'86 



Siliceous matter 53-75 



99-61 



" Other samples differ a little in the percentage of their constituents, but the 

 above may be considered a type of the general composition of ' Black Muck.' " 



