LITERATURE OF THE SUBJECT 501 



of the numerous limestone caverns. If it should be established that the iron 

 was first deposited as carbonate, its solution and decomposition were probably 

 accomplished by these acids previous to its oxidation and hydration. 



Kendall, J. D. : The Iron Ores of Great Britain and Ireland, London, 1893. 



The limoniteores are oxidized carbonates which are formed by replacement 

 of limestone. The direct source of the iron may have been the clay deposits, 

 but it originally came from volcanic rocks. In the replacement of limestone 

 by iron carbonate there would be a diminution of volume of about 18 per cent. 

 There would be a corresponding loss of 18 per cent in the change from car- 

 bonate to limonite. 



Kimball, James P. : American Journal of Science, September, 1891, and American 

 Geologist, December, 1891. 



The iron in solution replaces the lime carbonate in the limestones and is 

 subsequently oxidized. 



Leonhard, : Jahrbuch fur Mineral ogie, 1845, page 14. 



Describes the formation of ferric hydrate stalactites now going on in a mine 

 near cape Cornwall. Stalactites 18 inches long and an inch in diameter have 

 been formed since the mine was abandoned. It seems probable that these 

 were formed by waters carrying iron carbonate in solution. 



Lesley, J. P. : Proceedings of the American Philosophical Society, volume ix, 

 page 463. 



The ore is the residue of the Silurian slates and sandy limestones. The 

 geologist can procure specimens of every stage, from limestone which refused 

 to disintegrate and the iron-lime sandstone with the disintegration and crys- 

 tallization begun to the perfect ball and pot ore. 



Proceedings of the American Philosophical Society, volume xiv, page 19. 



The original source of the iron is the limestone, from which it is set free 

 during erosion. Three theories, each applicable to different kinds of ores, 

 are: 1, that part of the ores which occupied caverns, fissures, and sink-holes 

 now lie in pockets; 2, the deposits which show gravel and rolled ore and a 

 commingled mass of ore sand and clay are surface washes ; 3, there are inter- 

 stratified beds of brown hematite still in their original position, descending 

 between layers of sandstone and limestone to undetermined depths. 



Final Report of the Second Pennsylvania Geological Survey, page 364. 



It is quite possible that all the Great Valley limonites are cavern deposits of 

 very recent date, derived from the decomposition of a series of damourite lime 

 shales belonging to various horizons in the Chazy and Calciferous magnesian 

 limestones. 



Lyman, Benjamin Smith: Proceedings of the American Association for the Ad- 

 vancement of Science, 1867, volume 16, page 115. 



The ore was deposited in regular beds at the same time as the other rocks. 

 They have been broken into fragments at their outcrop, and the fragments 

 have accumulated in quantities varying according to the lay of the ground. 



