236 Scientific Proceedings, Royal Dublin Society. 



IRON. 



[The Irish iron ores occur in bedded masses and in veins. In the recent accumulations, 

 principally the alluvium and bog, iron occurs very frequently, often associated with 

 manganese ( Wad) as bog-iron-ore. In the Cainozoic rocks of Antrim and Deny are 

 allied ores known in the trade as the "Belfast Aluminous Ore," which occur as 

 bedded masses in the Eocene (?) Dolerytes. In the rocks of the Carboniferous period are 

 clayey chalybites, as nodules and layers in the Calp and Coal Measures, while in the 

 purer limestones of the same period, and the older Devonian, Ordovician, and Cambrian 

 rocks, are regular veins and bunches of hematite, limonite, and chalybite. Some of 

 the iron ores, however, in these older rocks, seem in part to be bedded or to partake of 

 the nature of the veins known as lay in lay, that is, they underlie in the bedding of 

 the associated rocks. Some, however, seem, and may be, more intimately connected 

 with the associated strata, as a portion of a bed or beds may have been ferriferous, 

 thus forming a bedded "bunch of ore." 



The localities where " bog-iron-ore" occur are so numerous, that it would be impossible to 

 enumerate them, but when particularly conspicuous they will be referred to. During 

 the smelting operation in the 16th aDd 17th centuries, when the Irish iron industry 

 appears to have been at its height, these bog ores seem to have been extensively 

 worked to mix with the other ores. At the present time a peaty variety is at times 

 extensively exported to England and Scotland, principally from Donegal, to be used 

 for the purification of gas and other purposes. In general, it is found as layers in 

 the peat, and may be from blackish to a dirty white in colour, but more often it is of 

 a pale yellowish green ; these, when exposed to the air, rapidly oxidize, changing in 

 colour to yellow or reddish yellow. The bog-iron-ore is employed by gas manufac- 

 turers to purify the gas from sulphuretted hydrogen. In the process the ore becomes 

 charged with sulphur, thereby becoming very valuable for the production of pure 

 sulphuric acid. The residue {brown ochre), is also valuable, being sold for the manu- 

 facture of paint. 



It appears remarkable, that the older deposits, especially in the alluvium, are of much 

 greater magnitude than any that are now accumulating. This possibly may be due 

 to the older masses being, in a great measure, the leaching from the surface rocks ; 

 which leaching process, being now long since accomplished, the present depositions 

 have to depend solely on the iron brought up in springs from more or less deep- 

 seated rocks]. 



