IRONSTONE FORMATION OF THE FOREST OF DEAN. 
275 
of the spot, situated in the midst of a thickly-planted wood, has 
obtained for the locality the name of the " Deyil's Chapel." 
In many of the worked-out *• churns," or " weeldons," there are 
considerable recent encrustations of carbonate of lime ; and the natural 
process of forming stalactites and stalagmites may be seen in operation, 
although nothing has yet been produced to compare, in picturesque 
beauty, with the strange forms which are met with in our more famous 
limestone caves. The extreme slowness of the progress made in the forma- 
tion of these encrustations is well demonstrated in the Sway-pole Mine, 
where the water holding the carbonate of lime in solution, drops equally 
on the floor of the churn and on the wall of a " brattice " or stopping 
erected in connexion with the former ventilation of the mine, at a period 
far beyond the memories, and even the traditions, of the oldest miners 
living in the district. A considerable thickness of stalagmite has formed 
on the floor, but on the wall of the brattice only a mere film of encrus- 
tation can be seen. Near the bottom of the " mine-measures," and 
following a general parallelism with the floor of the deposit in most of 
the mines on the south side of the Forest, a small irregular vein of 
reddle is to be traced, but which may, as it contains a large portion of 
alumina, be classed as an ochre. In shade it varies from a pale blood 
red to a rich madder brown, and is occasionally sufficiently intense in 
colour to rival the finest Armenian bole : it is exported from the Forest 
under the term " native red," and several hundred pounds' worth have 
been occasionally raised in a very short space of time from the same 
mine. The vein is known as the " Colour Spirt," and it was formerly 
a saying in the district that no " mine," meaning ore, existed below it. 
This, however, like other empirical dogmas, such as no copper west of 
Truro Bridge, in Cornwall, no coal beneath the Magnesian limestone in 
the north of England, &c., experience has proved to be false ; and in 
certain large joints, which cut across the limestone bed, or under-edge- 
stone, that underlies the "mine-measures," large deposits of brush 
ore are found occupying a position in the joint nearly akin to the 
phenomena presented in a true " lode " ; moreover, the upper portion 
of these joints, where they are near the surface, are fiUed with a highly 
ferruginous marl, already described as "clod-ore," which is so loaded 
with small particles of compact haematite as to occasionally show, 
by analysis, as much as 40 per cent, of iron. These joints have 
been proved at Bream to a depth of forty yards and upwards ; they 
