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- A system of joints in coal oblique to the bedding, at an angle of about 35 degrees to 75 degrees . Backs are usually perfectly tight and have polished cheeks which suggest a certain amount of movement. Back may be applied to the principal cleat. See also: backs; cleat.
- The roof or upper part of any underground mining cavity.
- The ore between a level and the surface, or between two levels. See also: back of ore
- That part of a lode which is nearest the surface relative to any working part of a mine, thus the back of the level or stope is that part of the unstoped lode which is above. See also: back of lode
- A joint, usually a strike joint, which is perpendicular to the direction of working.
- As applied to an arch, the outer or upper surface.
- The pavilion of a gemstone.
Source: Dictionary of Mining, Mineral, and Related Terms