On the Barytes Mines. 123 



sugar. Such at least is the Bantry native opinion. It is besides 

 occasionally useful for the manufacture of glazes for porcelain*. 



The mineral is worth about £1 per ton, delivered free on board 

 at Bantry, but when ground and prepared it fetches £4 per ton. 



A few words on the probable mode of formation of this mineral 

 may not be out of place. And first I may mention that many 

 of the Irish localities for veins of sulphate of Barytes appear to lie 

 in the Old Red Sandstone. Thus Portlock records its occurrence 

 in the Old Red Sandstone of Bally nascreen and Desertlyn, county 

 Derry, and Clogher, county Tyrone. But this is merely a coinci- 

 dence, because is it found here as in other counties in many other 

 rocks, crystalline and sedimentary, and in England it occurs largely 

 in the Carboniferous limestone. Now it is tolerably easy to 

 account for the presence of veins of this mineral in limestone, 

 which is easily soluble and quickly worn into fissures or pipes by 

 ordinary atmospheric water, in which, under some circumstances, 

 Barytes might be deposited, but the first difficulty with which we 

 have to contend in this case is the solution of such rocks as sand- 

 stone and slate. The Derryginagh deposit can be accounted for 

 by a simple fissure, but this will not account for the other case, in 

 which the original material has been removed in the form of a 

 nearly square pipe, which could never have been produced solely 

 by Assuring. There can be no doubt but this receptacle has re- 

 ceived its present form through the action of water. Doubtless such 

 pipes are due to fissures in the first instance which, allowing the 

 water to percolate freely, are eaten away bit by bit into their 

 present form. 



Age of these Veins. — As these veins run partly along and partly 

 across the strike of the strata, which lie in flexures dipping at 

 high angles, it follows that they must be of more recent date than 

 that of the upheaving and flexuring of the Old Red Sandstone 

 and Carboniferous rocks of the south of Ireland. Now, as Pro- 

 fessor Hull has shown, these flexures are due to forces acting at the 

 close of Carboniferous and previous to the Permian Periods. f It 



* It appears to me that the granular varieties might, with advantage, be substituted for 

 alabaster, for statuary and ornamental purposes. The mineral can be obtained in large 

 blocks. 



t Jour. Roy. Geol. Soc, Ireland, iv., pt. iii,, p. 114, 



