22 On the Geological Distribution of Gold. 



Cupreous ores existing with the auriferous veinstone, 

 naturally impart their metal to the gold, just as the auriferous 

 minerals, spread among copper ores, show a small quantity 

 of gold among tons of copper. These facts prove that the 

 hi-sulphurets of iron are the means by which gold is intro- 

 duced among copper ores, just as copper-pyrites among the 

 auriferous veinstone originates an alloy of copper in gold ; 

 and, therefore we find that copper is not a natural alloy of 

 gold in the veinstone, neither does this metal ever make an 

 alloy with the fluvial gold, silver being the only prevailing 

 and natural alloy of gold in general. Chemically pure gold 

 has not, as yet, been found in nature. 



The exterior appearance of gold from the rock is most 

 varied, both in size and configuration, from microscopical 

 particles to those increasing to the weight of from grains up 

 to pounds, though of the latter accumulations the rock gives 

 very rare examples.* Gold from the vein is occasionally 

 found in a free state on the surface of the mineral enclosing 

 the greater part of it, but mostly this metal exists in- 

 corporated with the mineral and metallic compounds constitu- 

 ting the gold-producing materials of the gang or vein. 

 The prevailing state is in an infinite variety of fungiform, 

 capillary, ramified and other most singular forms ; the la- 

 mellar form being rarely met with in gold from the rock. 

 Among such exceptions may be named what I saw in El 

 Valle de Osos of S. America, where some few thin gold 

 plates were found in fissures of quartz from one of the few 

 veins of that neighbourhood, exactly filling the seams, with 

 two lamellar pieces of gold 1^ inch long, § wide, and 1-64 of 

 an inch thick, forming a true parallelogram of nearly sharp 

 angles. This unbounded irregularity in the form of gold as 

 found in rocks, entitles this metal to the name of amorphous. 



"With regard to gold from fluvial deposits, whether ob- 

 served in the finest dust or in larger particles, its form 

 presents the greatest variety of fantastical configurations. 

 Among the fluvial gold is also found the deposition of crystals 

 in a cube, a regular octohedron and some other modifications, 

 though these are but rarely seen. Crystals of this or 

 any other form, as far as my experience goes, are not found 

 among gold in the rock. 



* In New South Wales, Australia, a quartz-block found on the surface, 

 contained various larger and smaller particles of gold of a pale yellow 

 coloiu-, of irregular and rough shape (fungiform) to the weight of 106 lbs, ! 



