 | 1907 - 1026 páginas
...7 to 10 feet are mined. Probably the maximum thickness is attained between Red Gap (near Irondiile) and Bald Eagle, although for a mile southwest of Red...thicker Big seam at a lower cost per unit of iron. The structure and composition of the Big and Irondale seams is shown in the following series of sections,... | |
 | 1907 - 532 páginas
...great thickness there are rarely more than 10 to 12 feet of good ore in a single bench, and at mostr places only 7 to 10 feet are mined. Probably the maximum...thicker Big seam at a lower cost per unit of iron. The structure and composition of the Big and Irondale seams is shown in the following series of sections,... | |
 | Geological Survey (U.S.) - 1907 - 532 páginas
...is attained between lied Gap (near- Irondale) and Bald Eagle, although for a mile southwest of lied Gap the bed remains nearly as thick. From northeast...thicker Big seam at a lower cost per unit of iron. The structure and composition of the Big and Irondale seams is shown in the following series of sections,... | |
 | 1908 - 1244 páginas
...Gap on the SE. Southwest of Lone Pine Gap the bed either consists of interbedded low-grade iron-ore and shale, or else its identity is completely lost. Its soft ore, now nearly all mined out either by surface-trenches or slopes, is the best in the district. Its hard ore is also of high grade, and hitherto... | |
 | Ernest Francis Burchard - 1910 - 248 páginas
...Pilot Knob on the northeast and Lone Pine Gap on the southwest. Southwest of Lone Pine Gap the bed consists of interbedded lowgrade iron ore and shale...nearly all mined out either by surface trenches or drifts, is the best in the district. Its hard ore is also of high grade and hitherto has been for the... | |
 | Geological Survey (U.S.) - 1910 - 246 páginas
...Pilot Knob on the northeast and Lone Pine Gap on the southwest. Southwest of Lone Pine Gap the bed consists of interbedded lowgrade iron ore and shale...nearly all mined out either by surface trenches or drifts, is the best in the district. Its hard ore is also of high grade and hitherto has been for the... | |
 | Ralph Arnold - 1910 - 958 páginas
...Pilot Knob on the northeast and Lone Pine Gap on the southwest. Southwest of Lone Pine Gap the bed consists of interbedded lowgrade iron ore and shale...nearly all mined out either by surface trenches or drifts, is the best in the district. Its hard ore is also of high grade and hitherto has been for the... | |
 | 1916 - 1150 páginas
...of low-grade ore and shale or losing its identity entirely. Burchard0 says of the grade of the ore : Its soft ore. now nearly all mined out either by surface trenches or drifts, is the best of the district. Its hard ore is also of high grade and has hitherto been for the... | |
 | 1907 - 1200 páginas
...either consists of interbeddeJ low-grade iron ore and shale or else its identity is completely !<*'• Its soft ore, now nearly all mined out either by surface trenches ur CLINTON ORES OF BIRMINGHAM DISTRICT, ALABAMA. slopes, is the best in the district. Its hard ore... | |
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... and shale, and is consequently of no possible value; and finally the upper bench itself becomes shaly and carries only a very low-grade ore. The Irondale seam is best developed on Red Mountain between Pilot Knob on the northeast and Lone Pine Gap... 