377 
Curl of Staffordshire . 
but, as it swells to a greater thickness, the size of the cones increases 
proportionally, until they are a foot in length from the apex to the 
base. 
In the mine which I inspected, [the Coppice-mine) the protube- 
rances are attached to the under side of the stratum of iron-stone, 
never to the upper ; and the base of the cone is placed downwards, 
its apex being directed towards the iron-stone. This is seen to be 
the case, where the stratum has suffered no disturbance, and, ac- 
cording to the information I received from the miners, the curl is 
not found in this district attached to the upper surface of the iron- 
stone in any instance. I have however observed masses of curl, 
into which the iron-stone penetrated so as to surround and inclose a 
portion of the curl. In these specimens, the apices of the cones 
were always presented towards the iron-stone, so that the bases of 
cones proceeding from opposite surfaces of iron-stone, were pre- 
sented to one another, and, but for a small interstice partly filled 
with clay, were brought into apposition. 
The stratum contains small veins of calcareous spar, passing ver- 
tically, and without interruption, through both the iron-stone and 
the curl beneath it. These veins intersect one another as in the 
reticulations of septaria. 
The Staffordshire curl has been recently employed in considerable 
quantities for making Roman cement , for which purpose it is burnt 
and ground to a fine powder. 
Curl, (or, as it is there called, curUstonep) is found in the 
Shropshire coal-field at Prior’s Lee, Sned’s Hill, and Ketley. At 
the Ketley iron-works it was once employed as a flux, instead of 
common limestone ; but its application to this use was abandoned. 
Its occurrence in that district is mentioned by Mr. Arthur Aikin, in 
the Geological Transactions, vol. I. p. 197. 
3 b 2 
