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Threlkeld Quarry, several joints having been met with, the sides 
of which are coated with crystalline quartz, galena, and blende. 
Similar quarrying or mining operations in other masses of igneous 
rock would no doubt afford like evidence of thermal action. 
In process of time the last trace of volcanic energy disappeared, 
the thermal waters ceased to flow, and the veins became conduits 
for the reception of surface drainage; then the water flowing in 
the opposite direction, that is downwards instead of upwards, 
would attack and dissolve some of the minerals previously deposited, 
and where circumstances were favourable, re-deposit them at lower 
levels in the same veins but under altered conditions, fresh 
combinations being formed by the addition of other minerals held 
in solution by the solvent fluid. This process has prevailed to a 
large extent in the veins of the Caldbeck Fells, decomposition 
products forming the largest proportion of the ores raised, while 
the sulphides of lead, copper, and zinc, were of secondary import- 
ance. This is no doubt due to the proximity of large masses 
of igneous rock on the side from which drainage would fall into 
the veins. The rain descending upon the igneous masses, having 
in its passage through the rock dissolved and carried away a certain 
amount of mineral matter, which on reaching the veins would unite 
with the minerals already deposited, or with those which were then 
being deposited there. It is to this combination of influences that 
the mines of the Caldbeck Fells are so justly famed for the great 
variety of rare and beautiful minerals which they yield, and of 
these, Roughtengill stands pre-eminent. It also stands foremost 
with regard to the richness of its deposits, which extend over a 
length of six hundred fathoms, yielding lead, copper, and zinc ores 
in workable quantities, and in a great variety of forms and colours, 
together with manganese and iron (limonite), also barytes and 
other non-metallic minerals. 
Driggeth, or Sandbed Mine, ranks next to Roughtengill in im- 
portance. It too, has yielded lead and copper in considerable 
quantities, also some zinc ore and barytes. There was very little 
galena raised at Driggeth, almost the entire yield of lead ore 
consisting of decomposition products. 
