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 Ballynascreen 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 asimple 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 fissuring. There can be no doubt but this receptacle has re- 
ceivedits 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 ehasé 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- 
afessor Hull has shown, these flexures are due to forces acting at the 
close of Carboniferous and previous to the Permian Periods.t It 
* It appears to me that the granular varieties might, with advantage, be substituted for 
alabester, for statuary and ornamental purposes. The mineral can be obtained in large 
blocks. 
+ Jour. Roy. Geol. Soc., Ireland, iv., pt. iii, p. 114. 
