OF ARKANSAS. 107 



with the bedding rock; but, nevertheless, there are crevices having a 

 connection with the ore, the bearing of which is nearly north and south, 

 opening occasionally into cavernous spaces, precisely analogous to the 

 ore-bearing veins in other parts of the state, and in Wisconsin and Iowa; 

 but these are either entirely barren of ore or contain only small quantities. 

 My impression is, that the lead ore once occupied these north and south 

 crevices, and was subsequently removed, in part or in whole, into its 

 present bed by a transposition, analogous to that known to minerologists 

 under the name of the pseudomorphous process, by which one mineral is 

 removed, while another takes its place, assuming often the form of the 

 first mineral, instead of the usual form belonging to itself. The term 

 " analogous " is used, because the lead ore here cannot exactly be consid- 

 ered to occur in a false form, or one belonging to another mineral; in this 

 instance, I believe, it only took the place of the amorphous rock; therefore 

 it was not infiltrated into a pre-existing geometrical mould, if I may so 

 express it, but had freedom of space sufficient to assume its usual cuboidal 

 structure. That it should be deposited like a limestone or sandstone, is 

 altogether improbable and contrary to the usual nature of such ponderous 

 and difficultly soluble minerals. 



The lead-bearing rock is not very fossiliferous, but there can be dis- 

 tinguished the Orthis crinistria, Productus cora, and other fossils of the 

 cherty barren limestone division of the subcarboniferous group; not, 

 however, belonging to the Archimedes and pentremital group, as has been 

 suggested. 



Though the profitable discoveries of lead ore at the Granby mines, have 

 hitherto been confined to about one mile square; still, they attracted a 

 population, in two years, of 3,000 people, to a section of land before 

 almost neglected, even by the farmer, and which now, with the unfavor- 

 able circumstance under which the mining claims are held, (being part of 

 a tract conditionally ceded to one of the proposed Pacific railroad routes), 

 has, nevertheless, in that short space of time, converted a wild prairie into 

 a populous town, full of enterprise and industry. 



It should be observed, too, that the surface indications were no more 

 encouraging, at the time the mines were started, than they are in many 

 localities that may be pointed out in the above counties in Arkansas, 

 where the same formation exists and where the cherty materials, thrown 

 out from excavations for wells, cannot be distinguished from the rubbish 

 rock at the mouth of the Granby shafts. I may add, too, that, in all these 

 counties, surface ore has occasionally been found under circumstances 

 similar to that in which they were first discovered in Newton county. 

 But still the search after lead ore may be precarious, and lead to many 



