On the Geological Distribution of Gold. 21 



ducing copper, tin, zinc, antimony, lead, nickel, and 

 bismuth, and also the ferruginous quartz (in Cornwall 

 known by the name of " gossan") are generally found 

 auriferous, though not so much so as to answer the 

 object of a commercial speculation. The hydrous oxide 

 of iron * also termed bog-iron ore, and found abundantly 

 distributed in most parts of the world, will always prove 

 auriferous. In South America this ferruginous compound 

 having been observed from various localities, has invariably 

 produced some gold; this metal being distributed in micro- 

 scopical particles. In corroboration thereof, it may be stated, 

 that a vast deposit of hydrous iron-ore in Hanover was 

 lately examined and duly analysed by A. T. Abel Esq., of 

 Hamburg, and found not only auriferous but even rich in 

 gold, so as to present a remunerative field for speculation in 

 two branches of mining enterprise, i.e., for iron and gold. 

 Wherefore, there exists every reason to believe that gold is 

 more widely spread over the earth's surface than has here- 

 tofore been imagined. 



Metallic compounds existing in auriferous veins but rarely 

 carrying gold : — 



Bi-sulphurets of zinc, antimony, arsenic, white oxide of 

 antimony, chromate, phosphate, and molybdate of lead ; also, 

 carbonate of bismuth. t 



White pyrites, often found in the rocks adjacent to the vein, 

 or in rocks forming the bed for fluvial depositions carrying- 

 gold, or occupying crevices of decayed or petrified wood 

 among fluvial detritus, does not produce even traces of gold. 



Hydrated oxide of iron, found in a very fine powder, 

 encloses a microscopical gold-dust, partly to be detected on 

 the deep-brown ground of a velvet appearance, as is observed 

 not only in South America, but in other quarters of the 

 world. The gold-particles found among the specular iron- 

 ore are always found of a lamellar shape, and small size. Sul- 

 phurets of copper when auriferous, produce gold in very small 

 particles, of angular shape. The mixed oxides of iron and 

 copper prevailing in Peru, there called " Pacos," produce a 

 diminutive gold, also of angular shape, often proving very 

 rich. Gold has also been found in veins producing quicksilver, 

 ore, but not involved in cinnabar. 



" * It is supposed that this compound originates from decomposed pyrites ? 



t Carbonate of bismuth, with some oxide of iron, containing about 60 

 per cent, of gold, has been found at Kingower, Victoria ; a sample of this 

 rare compound was kindly presented to the writer by Wm, Birkmyre, Esq. 



