156 Scientific Proceedings, Royal Dublin Society. 



perty in the lithomarge. Also the peat water seems to have a 

 solvent action on the dolerite, from whence it probably draws its 

 supply of manganese and iron, as stones taken from the bogs 

 have white envelopes of -g to 5 inch in depth, in which there is 

 scarcely a trace of iron, while below this crust the dolerite is 

 dark and very little altered. It may also be mentioned that in 

 the mountain bogs lumps of cellular iron ore are found with the 

 cells filled with oxide of manganese. If these solvent and preci- 

 pitating actions are at all general, which they ought to be, de- 

 posits of manganese should be going on in various places in con- 

 nexion with the trap area.* 



The Ochreous rock over the lithomarge is called "pavement" by 

 the miners, as it forms the floor or pavement of the iron ores. In 

 it the levels and tunnels for extracting the ore iire usually driven ; 

 it is a soft rock and can easily be cut with the pick. The pave- 

 ment seldom contains bauxite, except where it is traversed by a 

 dyke, near which the spots are large and numerous. 



In general on the pavement, the aluminous or second ore occurs, 

 in the upper portions of which are scattered pisolites (peas of the 

 miners) of iron, and resting on this is the " first " or " pisolitic " 

 ore. In the latter the pisolitic structure is always best developed 

 at the top of the bed, it also being the richest portion, containing 

 larger and more numerous pisolites than lower down. 



The pisolitic ore varies from twelve to twenty inches in thick- 

 ness, but occasionally reaches twenty -four or even thirty inches. 

 In colour it varies from red through brown to black, some of the 

 latter coloured pisolites shine like graphite ; the red ores always 

 are over the others ; generally, however, the seam of pisolitic ore 

 is of one colour throughout its thickness, this in the Glenariff 

 district is usually dark brown or black. It is the matrix oi' 

 cementing material for the most part that gives the colour to the 

 ore, the pisolites are generally black, though in red ores they 

 sometimes take a red colour, but of a darker shade. 



Near the " face " or cliff outcrop of the seam the ores are soft, 

 the pisolites being in a friable mass of peroxide of iron, but as 

 the bed is followed in, it becomes harder and the pisolites are 

 cemented firmly in the matrix ; while at twenty to thirty fathoms 

 from the outcrop the ores are usually too hard for pick working 



* See Notes added in Uie Press. No. 2. 



