 ... concerning the genesis of the hard ore itself. The mode of occurrence and the constitution of the hard ore do not indicate that it has resulted from the alteration of a rock originally very different in composition, or that it is directly residual...  Bulletin of the United States Geological Survey - Page 125by Geological Survey (U.S.) - 1910Full view - About this book
 | Ernest Francis Burchard - Coal mines and mining - 1910 - 248 pages
...hard ore with depth. This fact indicates clearly that the soft ore has been derived by a secon dary process from the hard ore, but it does not furnish...containing minor quantities of iron minerals. The hard ore mtist therefore be regarded as having been formed in essentially its present condition contemporaneously... | |
 | Tennessee. Division of Geology - Geology - 1913 - 214 pages
...the outcrop, merges more or less gradually with depth into hard ore of fairly uniform composition. This fact indicates clearly that the soft ore has...composition, or that it is directly residual from disinteg(^tion of rocks containing minor quantities of iron minerals. The hard ore must therefore be... | |
 | 1932 - 720 pages
...and quality of unexploited ore. The soft ore merges more or less gradually into hard ore with depth. The mode of occurrence and the constitution of the...ore must therefore be regarded as having been formed by sedimentation in essentially its present condition. Where lime was replaced by iron this process... | |
 | Geology - 1932 - 200 pages
...and quality of unexploited ore. The soft ore merges more or less gradually into hard ore with depth. The mode of occurrence and the constitution of the...ore must therefore be regarded as having been formed by sedimentation in essentially its present condition. Where lime was replaced by iron this process... | |
 | Chester Ray Longwell - Geology - 1933 - 360 pages
...and quality of unexploited ore. The soft ore merges more or less gradually into hard ore with depth. The mode of occurrence and the constitution of the...ore must therefore be regarded as having been formed by sedimentation in essentially its present condition. Where lime was replaced by iron this process... | |
 | Mineral industries - 1908 - 698 pages
...has been derived by a secondary process from the hard ore, but it does not fornish any suggestions concerning the genesis of the hard ore itself. The...originally very different in composition, or that it is in any way residual from disintegration of rocks containing minor quantities of iron minerals. The... | |
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