 | Elmer Fred Davis - Sandstone - 1919 - 832 pages
...chert, taconite, or ferruginous slate, where softer and more or less hydrous. These rocks become ore by local enrichment, largely by the leaching out of...to a less extent by the introduction of iron oxide. There are accordingly complete gradations between them and the iron ores. . . . Local phases of the... | |
 | Washington Academy of Sciences (Washington, D.C.) - Science - 1911 - 342 pages
...chert, taconite, or ferruginous slate (where softer and more or less hydrous). These rocks become ore by local enrichment, largely by the leaching out of...to a less extent by the introduction of iron oxide. There are accordingly complete gradations between them and the iron ores. One of the most significant... | |
 | Elmer Fred Davis - 1915 - 266 pages
...chert, taconite, or ferruginous slate, where softer and more or less hydrous. These rocks become ore by local enrichment, largely by the leaching out of...to a less extent by the introduction of iron oxide. There are accordingly complete gradations between them and the iron ores. . . . Local phases of the... | |
 | 1922 - 84 pages
...result of the local enrichment of the lu¿matite-quartzites and sometimes of the ferruginous shales, largely by the leaching out of silica, and to a less extent by the introduction of iron oxide. The hmema.tite deposits of the Singhbhum district have recently been examined by Mr. Ernest Parsons... | |
 | University of California (1868-1952) - Geology - 1918 - 702 pages
...chert, taconite, or ferruginous slate, where softer and more or less hydrous. These rocks become ore by local enrichment, largely by the leaching out of...to a less extent by the introduction of iron oxide. There are accordingly complete gradations between them and the iron ores. . . . Local phases of the... | |
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by local enrichment, largely by the leaching out of silica, and to a less extent by the introduction of iron oxide. 