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Board of Commissioners for the Second Geological Survey, 1876
 

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Σελίδα iii - WILSON, MD, Clearfield. Hon. DANIEL J. MORRELL, - Johnstown. HENRY W. OLIVER, Pittsburg. SAMUEL Q. BROWN, Pleasantville. SECRETARY OF THE BOARD JOHN B. PEARSE, Philadelphia. STATE GEOLOGIST PETER LESLEY, ------ Philadelphia.
Σελίδα 133 - ... the slates seem to merge by imperceptible degrees in a direction normal to the plane of bedding, first into completely metasomatized pseudomorphs of limonite after pyrite (but still retaining the form of the latter) ; then, the same with a kernel of pyrite ; then the pyrite itself, first with a shell, and then with a mere stain of ferric hydrate ; and finally the same slates * A-urofal limestone of Rogers. are revealed porphyritic from the pyrite, and not at all decomposed.
Σελίδα 137 - An interesting inquiry is here suggested as to what can have been the geological atmospheric condition which produced the remarkable percolation which carried down so large an amount of ore out of these ferruginous beds. Was it tepid rain charged with carbonic acid in an early...
Σελίδα 137 - ... the question has been asked me, Where are the evidences of the organic material which was required to produce the vast beds of iron-ore found in the ancient crystalline rocks? I answer that the -organic matter was, in most cases, entirely consumed in producing these great results ; and that it was the large proportion of iron diffused in the soils and waters of...
Σελίδα 137 - ... which are insoluble in water and in many acids, and are thus conveniently separated from a great many other bodies. Now, when in a water holding iron-oxide, sulphates are also present, the action of organic matter, deoxidizing the latter, furnishes the reagent necessary to convert the iron into a sulphide ; which in some conditions, not well understood, contains two equivalents of sulphur for one of iron, and constitutes iron-pyrites. I may here say that I have found that the unstable protosulphide,...
Σελίδα 137 - I answer that the organic matter was, in most cases, entirely consumed in producing these great results ; and that it was the large proportion of iron diffused in the soils and waters of these early times, which not only rendered possible the accumulation...
Σελίδα 139 - The theory of the alteration in situ of various iron minerals resulting in the formation of many of these limonites, advanced by CU Shepard many years ago, and ably discussed and accepted by Dr. TS Hunt, cannot bo disregarded in seeking the causes which produced these limonites.* [*In 1838, and independently of Prof.
Σελίδα 137 - With reference to the Ferric Sulphide or pyrite, the same author ascribes its formation to the deoxidizing agency of decaying organic matters out of contact with air on soluble sulphate of lime and magnesia, giving rise, if carbonic acid be present, to Hydrogen Sulphide.
Σελίδα 138 - Sulphate has been produced. That this molecule of free sulphuric acid in its passage over the mica and chlorite slates has dissolved out part of their alkalies, especially soda. That this solution of sodium sulphate has mingled in the clay beds below with the solution of calcium bicarbonate, produced by the drainage of rain waters over the limestone beds, giving rise to sodium bicarbonate and calcium sulphate. That this sodium bicarbonate reacting on the "Ferrous Sulphate has precipitated Hydro-Ferrous...
Σελίδα 134 - If the former hypothsis be the true one, we should expect to sec an absence of limestone in the vicinity of the large deposits ; for, granting for the moment that the limestone contain enough pyrites to account for the entire deposit, (a fact which at least admits of some question,) a percolation of water sufficient to oxidize the sulphur of these pyrite crystals and carry away enough iron to produce the beds, would entirely honey-comb and finally, both by solution and attrition, dissipate the pyritiferous...

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