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 " Devil'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. N'ear 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 Torest, 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 filled 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 



