438 ON THE GEOLOGY OF THE 
The ironstone which occurs along with this, is of no great 
consequence, nor perhaps very general : it is not converted to 
any useful purpose, so far as I could learn. 
There is another substance which occurs here and there 
among the beds of the second limestone, analogous to the mu- 
latto limestone of Antrim, which 1 believe to be a compound 
of carbonate of lime and granular augite, similar to the coccolit 
of Andrada, but much finer in the grain. In both, the colour 
is dark green, and when the calcareous matter is separated by 
’ means of acid, the coccolit remains in minute dark-coloured 
grains. In Ireland, however, it occurs in more regular strata, _ 
and of considerable extent, always under the white limestone, 
and with the grains of augite pretty uniformly dispersed 
through it. Here the beds appear to be mere adventitious 
deposites, maintaining no conformity with the accompanying 
strata, extremely irregular, and of small extent. Sometimes 
they are entirely composed of the coccolit, when they are of a 
very dark green colour, and very friable: in this state, the sub- 
stance is used in the manufacture of Pigments. It is generally, 
however, dispersed through the limestone, in which state it forms 
a very beautiful rock. ‘Here, as well as in Ireland, it usually 
contains organic remains; besides some bivalves, the belem- 
nite, the cornu ammonis, and the nautilus, are the shells which 
I have generally seen in it. It assumes positions high and 
low, and may be considered an independent member of the 
Second Limestone Formation. 
There is another variety of limestone, evidently of a subse- 
quent date, which also occurs in this vicinity, but on so small 
a scale, that it is scarcely deserving observation. In one place 
only I noticed it on the road leading from Nice to Ville Franche, 
where it lay in thick beds of a soft earthy texture, and con- 
taining a quantity of vegetable remains. It is of a green- 
ish-grey colour, and probably a species of calcareous tuffa, 
which, 
