WATSOX — NOTES ON METALLIFEROUS SADDLES. 



365 



ing, while sometimes tliej are also sufficientlj numerous to repay the 

 cost of removmg the whole of the rock contaimng them. But the 

 ore-bearing parts of the saddles extend in reality to two separate sets 

 of beds, distinguished as the tliich and the thinheds,ff' and g g' (tig. 

 4), the latter being immediately under the former. The mineral, hh' , 

 is associated in the thin beds, g g' , under nearly similar conditions to 



Lign. 4.— Vertical section of the " beai'ins: beds," sliOYfiiig the mode in ^Yhich the ore is 



deposited. 



those which have been described above for the thick beds (//') ; the 

 ore deposits in the former are generally worked by driving cross-cut 

 levels from the troughs of the thick beds (see dotted line o o' in the 

 lignograph). ISTo true vein-stone accompanies the ore in the saddles, 

 but crystallized calc-spar is not unfrequently plated with ore on the 

 cheeks of the fissures^ and spar also exists beneath the ore on the 



