108 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 9, 



form on a large scale, yields an excellent sparry ore, of which the 

 following analysis was made in Dr. Percy's laboratory : — 



Peroxide of iron 0*81 



Protoxide of iron 43'84 



Protoxide of manganese 12*64 



Lime 0-28 



Magnesia 3-63 



Carbonic acid 38*86 



Water 0*18 



Insoluble residue 0*08 



100*32 



At Eyesen Hill, intermediate between this point and Exmoor, the 

 lodes run much in the usual strike of E. by S., with a dip of 60° S., 

 but are unusually curvilinear for short distances, and, thus, "bunchy" 

 as regards their productiveness, being at times pinched up to a few 

 inches, and rapidly opening to 8 feet in width. They yield excel- 

 lent brown ore, of the variety called pitchy ore (Eisenpecherz) ; and 

 the occurrence of a small vein on the east side of the hill, coursirig 

 W.N'.E., is additional evidence in favour of the true vein-character 

 of these deposits. 



A very important lode stiU to be noticed is that of Huel Eliza, 

 worked some years ago, in the vaUey of the river Barle, for copper- 

 ore, but presenting in depth a mass of sparry iron-ore, with small 

 disseminated portions of copper-pyrites, in a manner similar to that 

 of some of the veins in the noted iron -district of Siegen and Miisen, 

 near Bonn. Brown iron-ore, ceding in depth to the carbonate, 

 occurs again in similar veins at Kentisbury Down. 



The principal geological results derived from an examination of 

 these lodes appear to be — 



1st. That a series of parallel fissures have been opened in planes 

 very nearly concordant with those of the general stratification, and 

 have then been filled with carbonate of iron, some quartz, and frag- 

 ments of the containing rock. Some of these, with the slates, have 

 afterwards been subjected to various disturbances, the results of 

 which are seen in heaves and slides, as at Goosemoor, near Bearland 

 Wood, &c. 



2ndly. This ore has (and in some places to a very great depth) 

 been entirely metamorphosed into goethite, or pure hydrous per- 

 oxide — ^the carbonic acid being removed, and the oxide of manga- 

 nese, which was originally as a carbonate involved in the same 

 compound, occurring in the new ore as a peroxide, — whilst the rhom- 

 bohedral structure is stiU distinctly shown in the entire mass, and 

 the cavities formed by the decrease of bulk consequent on the change 

 have given occasion to the appearance of innumerable brilliant aci- 

 cular crystals of goethite. 



3rdly. Some portions of the same vein -stuff, and, as it would 



