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a. The rock immediately above a coal seam. It is commonly a shale and is
often carbonaceous in character and softer than similar rocks higher up in
the roof strata. The roof shale may contain streaks and wisps of coaly
material, which tends to weaken the deposit. Roof in coal mining
corresponds to hanging wall in metal mining. See also:
roof stone Nelson
b. In mine timbering there are two classifications of roof, the immediate
roof and the main roof. The immediate roof lies directly over the coal and
may be a single layer or several layers of rock material of the same, or
different consistencies, and from a few inches to several feet in
thickness. This roof requires timbering to support it as the coal is
removed. The main roof is the roof above the immediate top, and may vary
from a few feet to several hundred, or even thousands of feet in
thickness. This roof is generally controlled by leaving pillars of solid
coal that will support its weight. Kentucky
c. The country rock bordering the upper surface of an igneous intrusion.
CF: floor
Source:
Dictionary of Mining, Mineral, and Related Terms
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