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Author: Admin | 2025-04-28
Shaft mining is synonymous with underground extraction. The lodes instead of being worked only at surface are encountered and exploited at depth. The details concerning this technique are complex, but the existence of abundant, good quality, contemporary and later literature made it possible to examine this particular aspect of the tin industry, which, because of its subterranean character was neglected during field survey.The details of shaft mining and its associated terminology gleaned from various sources are most easily expressed in diagramatic form and Figure 3.2 shows the character and position of the many elements in a typical mine.In brief, the development and exploitation of a cassiterite lode generally took the following form:i. Location and definition of the richness, strike and inclination of the lode [Details of this technique are considered here.ii.Digging of a shaft to intercept the lode at the anticipated depth. In Cornwall, most of the lodes were inclined sharply and thus a vertical shaft placed a short distance to the upper side of the outcrop incline, would have generally encountered the lode. At many sites the procedure of utilising vertical shafts was not adopted and instead they were dug directly onto the lode and followed its incline downwards. This had the advantage of allowing continual recovery of “paying” lode material instead of the barren rock encountered in the digging of vertical shafts through “dead ground”. The primary disadvantage, however, was that the inclined character of the shaft made it more difficult to remove the ore.iii. Once a vertical shaft had reached the lode, an adit would have been cut to run along its length, in order to examine its character and establish whether its extraction would be worthwhile. For an inclined shaft adits would also be cut at various depths to exploit the axial length of the lode. The material mined would either be taken to surface through the shaft or through another adit, which may have been dug from the valley bottom below the shaft, and driven to connect with the mine. This second adit would have drained the ground above this level, as well as making
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