APPLICATION" OF GEOLOGY TO MINING. 



economical advantages which the science is calculated to 

 confer, its assistance to the miner may be first adduced, 

 since it occurs earliest in the series of geological formations. 

 It is at once the object and the boast of geology to redeem 

 the search after metallic ores from the hazard which in times 

 past attended it ; to teach the miner to discard the belief 

 in sinister influences and evil spirits, by showing that 

 mineral substances have not been distributed by chance, 

 but that each is referable to some peculiar geological deposit, 

 to direct the inquiry for them on fixed principles, and in 

 conformity with the laws which regulate their occurrence. 

 In this country, the granitic regions are the only districts 

 in which tin is discovered in sufficient extent and abundance 

 to justify its being sought for economical purposes. Copper 

 is also found in the greatest abundance in granite, and 

 in the schistose or slaty rocks above it ; and the principal 

 mines of these metals, in this country, are situated in 

 Cornwall ; though the latter substance also presents itself, 

 but in less plenty, in the new red sandstone. Lead is 

 chiefly confined to the carboniferous limestone: the most 

 important supplies exist in Derbyshire and Scotland, 

 amid strata appertaining to this formation. These metals, 

 together with silver and others, occur in veins, which, 

 in some cases, communicate with fissures beneath, and 

 have, probably, been occasioned by deeply seated subter- 

 ranean agency ; or they are the result of the chemical 

 segregation of metallic particles from the surrounding 

 mass. Grold offers an exception to the general rule -of 

 metals existing in veins: it is disseminated in minute 

 quantities throughout those rocks (usually of a quartzose 

 character) in which it occurs, and is chiefly obtained in 

 alluvial gravel resulting from the decomposition of such 

 rocks, or from the sands of rivers, which, flowing over them, 

 have washed out the particles of gold. It is in the alluvial 

 soil on the banks of the Bio del Sacramento, that the rich 

 gold washings occur which have attracted so many " diggers" 

 to the shores of California, where the search is now pur- 

 sued with so much eagerness and success.* Platinum, toge- 

 ther with zircon, the diamond, and many other gems, is 



* Humboldt's Views of Nature, p. 207 ; Bolm's edition. 



