March io, 1893. J 



SCIENCE. 



131 



NOTES ON THE FORMATION OF THE IRON ORES' 



BY JAMES D. ROBEETSON, E.M., JEFFERSON CITY, MO. 



Among the deposits of iron ores in Missouri, those of specular 

 hematite in the sandstones of the Ozark region, although not so 

 well known as the porphyry ores, are an important and extremely 

 interesting class. These deposits are found in caves in the Ozark 

 series of limestones and sandstones, heretofore considered of 

 Lower Silurian age, and the equivalent of the Calciferous sand- 

 rock of New York State. From recent investigations of the Mis- 

 souri Geological Survey, there is reason to believe that these rocks 

 are of Cambrian age. 



At Cherry Valley, in Crawford County, there is a large deposit 

 of specular hematite of this class. It occupies a depression in the 

 strata formed by erosion and undermining. The ore is a good one 

 for foundry purposes, and is smelted at the Midland Furnace, 

 about six miles distant from the bank. The ore in the upper 

 portion of the bank is harder and more silicious than that found 

 deeper. It carries silica in the form of amorphous yellow ja.^per 

 and also as quartz. The quartz is found in very perfect, smgly 

 terminated crystals, both colorless and amethystine, and of a daik, 

 smoky color, the latter being due to included crystals and frag- 

 ments of hematite. Specimens are in the Survey colleiHion of 

 perfect crystals of amethystine quartz, studded with crystals of 

 specular hematite and frosted with minute acicular crystals of 

 goethite of a beautiful golden-brown color. The ore has many 

 vugs or cavities, which are lined completely with cr\stals of 

 hematite, magnificently colored — red, golden-brown, peacock- 

 blue, green, etc. While examining a number of these specimens 

 lately, the writer's attention was drawn to the peculiar appear- 

 ance of one, the markings of which had a great resemblance to 

 the stem of a crinoid, while in another part of the same specimen 

 there was a somewhat indistinct impression of a stem and cup of 

 a crinoid. The specimen in question was submitted to Professor 

 Van Hise of Madisou, Wis., and by him to Dr. Birge, professor of 

 zoology in the Wisconsin State University. These gentlemen say 

 that there is not the least doubt in their minds of the organic 

 origin of the peculiar markings of this specimen. Since then one 

 more specimen of like nature has been found. 



These organic remains, occurring in the deposit of specular ore 

 just described, have a significance perhaps not wholly seen at 

 first glance. They indicate that certainly a portion of the ore in 

 these deposits has been formed by direct replacement, molecule 

 by molecule of limestone by the iron from ferruginous waters. 

 They also suggest that the chert, which is so abundant in these 

 limestones, was the source of the silica in the ores. It is thus 

 very probable that the iron was originally substituted as carbonate 

 and subsequently concentrated and oxidized. The following 

 terse statement by Professor Van Hise in regard to the deposit 

 formed in a peculiar manner in Wisconsin is applicable here : ^ 

 " The chemistry of the process assumes the following: that the 

 oxygen of the percolating waters is sufficient to oxidize iron car- 

 bonate not in solution, and set carbon dioxide free ; that the resulted 

 carbonated waters are sufficient to take iron carbonate in solution ; 

 that if such waters bearing dissolved carbonate are mingled with 

 waters bearing oxygen, the iron carbonate, or a portion of it, 

 will be precipitated; that silica may be carried in percolating 

 waters; that a carbon dioxide solution sufficient to precipitate 

 silica by dilution may be made so weak in carbon dioxide that it 

 would be capable of taking silica into solution. All of these facts 

 and principles of chemistry are so well known that no discussion 

 of them or reference to authority is needed." 



One more question affected by these specimens is that of their 

 age. While the fossil forms are too indistinct to identify the 

 species, they are undoubtedly of Lower Carboniferous age. This 

 suggests the idea that Lower Carboniferous rocks extended at 

 least to this distance over the central portion of Missouri, and 

 further that these deposits of iron ore had at least not ceased 

 forming until after this period. These ore deposits, as stated 

 before, are found in Cambrian rocks, but the precise period of 



J Published wilti the approval of Arthur Wlnslow, State Geologist of Mis- 

 souri. 



a Am. Jour. Scl. CHI), vcl. xxxvll., p. 4.3. 



their furmation cannot be determined from our present knowledge 

 of the facts in the case. So far, but one deposit of Lower Car- 

 boniferous rocks has been found in place anywhere near here, 

 and that is a very small one. The writer has found fragments of 

 chert with Burlington fossils on the hills some thirty miles west 

 of here, but, with these exceptions, knows of no deposits of these 

 rocks nearer than St. Louis County. 



It is evident, therefore, that erosion has played an important 

 part in removing the mantle of Lower Carboniferous rock, and it 

 is probable that this agency at the same time prepared the under- 

 lying Cambrian rocks for the reception of the iron ores. 



It is not within the scope of this article, however, to demon- 

 strate the questions of the origin and age of these deposits, but 

 merely to record the occurrence of these organic forms and to 

 suggest their probable meaning. These questions are treated in 

 a much fuller manner by Mr. Frank L. Nason, in the recently 

 issued report of the State Geological Survey, on the Iron Ores of 

 Missouri. 



NOTES AND NEWS. 



An important meeting of the Victoria Institute, London, Eng- 

 land, took place last month, when Mr. J. W. Slater, F.C.S., 

 F.E S.. read a paper in which he traced the difference between 

 life and the physical forces, and reviewed all those experiments 

 and arguments by which some had sought to prove that a key to 

 the origin of life had been obtained. Contributions to the dis- 

 cussion of the question were made by Sir George Stokes, Bart., 

 V.P.R.S., who stated that Lord Kelvin's recently alluded to sug- 

 gestion that the germs of life on this earth might have come from 

 the bursting of a remote star, was only intended by him to refer 

 to the possible transmission from one part of the universe to an- 

 other of life germs, but that the first origin of life itself we must 

 all refer to God. Professor Lionel Beale, F.R.S., in supporting 

 Mr. Slater's views, said that an absolute line must be drawn be- 

 tween the living and the non-living. Living matter was distin- 

 guished from all other matter by a property, power, or agency, 

 by which its elements were arranged, directed, and prepared to 

 combine according to a pre-arranged plan for a definite purpose. 

 There was no gradual transition from the non- living to the living. 

 Life was a special position independent of and not in any way 

 related to the physical forces, it had nothing in common with 

 any material forces, powers, or properties, and holding in the 

 cosmos a remarkable and peculiar place. Professor Bernard of 

 Dublin pointed out that all evidence went to show that vital forces 

 are unique and not comparable with any other forms of energy. 

 Dr. Rae, F.R.S., contributed some valuable remarks, as also did 

 Dr. Biddle, the Revs. R. Collins, M.A., J. H. Clarke, and W. A. 

 Pippet. Dr. F. Warner, M.D., F.R.C.P., made several valuable 

 remarks on the question, which was also spoken on by Dr. Shettle 

 of Reading, Dr. Schofield, and others. Dr. Schofield was very 

 interesting in those remarks in which he pointed out what may 

 be called the history of the controversy in regard to life and the 

 physical forces, and in concluding he specially referred to the 

 dictum of Professor Huxley, viz., "Life existed before organism 

 and is its cause." Whatcthat cause was the Christian philosopher 

 fully recognized. 



— J. B. Lippincott Company announce for immediate publica- 

 tion a new (third) edition of the "Life of Benjamin Franklin," 

 edited from original manuscripts and from his printed corres- 

 pondence and other writings, by Hon. John Bigelow. Since the 

 appearance of the previous editions the author has been able to 

 secure considerable new and important information never before 

 published, which is incorporated in the new woi k. This edition 

 also contains several additional interesting illustrations. The 

 work is bound in three volumes, as heretofore. A new edition 

 of " Our Own Birds " has just been issued by J. B. Lippincott 

 Company. The volume contains a natural history of the birds 

 of the United States, revised and edited by Edward J. Cope. Cor- 

 responding Secretary of the Academy of Natural Sciences, Phila- 

 delphia. Although the first edition was profusely illustrated, 

 twelve new half-tone plates have been introduced, which greatly 

 add to the value of this edition. 



