49 



find conditions which, can only be accounted for by the action 

 of waters highly charged with mineral matters (in solution,) 

 being, indeed, the medium or carrier from the metallic sources, 

 where atom by atom it was taken up in solution, and subsequently 

 deposited or precipitated in the vein. 



As regards Ironstone veins, many doubtless may be filled by 

 the process of sublimation (esoteric,) either from great depths or 

 through igneous agencies not deeply seated (as some of the 

 specular ores of Iron;) or partly, if not entirely, through the 

 action of, or by means of infiltration (exoteric,) as in the 

 Hydrated Oxides in question : and it may be said that these are 

 the only ore veins whose origin we may perhaps ever determine. 

 For when we take a general view of the filling-in of the 

 dislocations in a district, whether termed faults, lodes, or cross 

 courses, we distinctly see that it has depended upon conditions 

 among which the mineral character of the adjacent rocks holds 

 a prominent place, and upon this character seems to have 

 greatly depended the nature of the chief mineral substances in 

 them. Among the Limestones we find Carbonate of Lime; — the 

 sandstones or SiHcious Rocks, Quartz, &c. We may therefore 

 rightly infer that either water charged with mineral matters in 

 suspension, derived from the adjacent rocks, has infiltered into 

 the fissures, or that the Hqiiid contents have acted on the 

 adjoining rocks, and dissolved and deposited a portion of them. 

 And upon the mineral characters of the adjacent rocks seems 

 also to me to have greatly depended the accumulation of the 

 ores of the useful metals. 



Or, if we may sum up the different theories, or those generally 

 received, they may be divided into — first, the contemporarieous 

 formation of mineral veins, with the rocks which enclose them : 

 secondly, the fi llin g-in of fissures formed in rocks by the 

 sublimation of substances driven by heat from beneath upwards: 

 and, thirdly, the fiUing of fissures in rocks by chemical deposits 

 from substances held in solution in the fissures, and by infiltra- 

 tion, such accumulations and deposits being, perhaps, greatly 

 due to electro-chemical agency. It is to this latter in the 

 main, and at the age I have mentioned, that I beHeve the Iron 

 lodes and ores of the Tortworth district were accumulated. 



