CHAPTER II. 



NOTES ON FOREIGN OCCURRENCES OF QUICKSILVER. 



There are few districts besides those of the Pacific Slope in which mer- 

 curial ores are met with in such abundance as to be of great commercial 

 importance. The Almaden mines, in Spain, take the first rank, and those 

 of Idria, in southern Austria, have yielded and will continue to yield a con- 

 siderable product. Several thousand flasks a year are also extracted from 

 the Tuscan mines. China now produces little quicksilver, though she for- 

 merly exported it, besides supplying the home demand. This is not due to 

 the exhaustion of the mines, and there seems to be good reason to suppose 

 that the deposits of Kwei-Chau are of great extent and value. Peru has 

 yielded very large quantities of quicksilver in former times, but the mines 

 are in part exhauftted and in part have been ruined by bad mining. While 

 the number of highly productive localities is small, the localities in which 

 ores occur are very numerous, and many of these have been of temporary 

 or local importance. The geological interest attaching to a locality is not 

 dependent upon the amount of metal which it has furnished to the markets 

 of the world, but upon the relations between cause and effect which the 

 occurrence serves to elucidate, and a brief review of the deposits known to 

 exist away from the Pacific Slope will form the fittest introduction to the 

 subject of this memoir. 



It will appear in the subsequent chapters that nearly every mineral 

 association and mode of occurrence known to exist elsewhere is repeated in 

 California and Nevada, so that the mercurial deposits of the Pacific Slope 

 admirably represent those of the world so far as they are known. 



I have inade no systematic endeavor to exhaust geological literature 

 with reference to foreign occurrences of mercurial ores, though it is certain 

 that no very important deposits have escaped me. I have sought to compile 



