 Its soft ore, now 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 most part held in reserve, since ore could be produced from the thicker Big seam...  Bulletin of the United States Geological Survey - Seite 138von Geological Survey (U.S.) - 1907Vollansicht - Über dieses Buch
 | 1908 - 1244 Seiten
...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 Seiten
...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 Seiten
...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 Seiten
...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... | |
 | 1909 - 822 Seiten
...thickness is attained between Red Gap (near Irondale) and Bald Eagle, although for a mile southwest of Red Gap the bed remains nearly as thick. From northeast...thicker Big seam at a lower cost per unit of iron. According to texture the Clinton ores are of two varieties, viz: (1) fossil ore and (2) oolitic ore.... | |
 | 1907 - 1200 Seiten
...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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