On the Geological Distribution of Gold. 23 



Gold in its natural state is always found alloyed with 

 silver. When copper partakes of the alloy, it may be viewed as 

 accidental, as has been alluded to in a foregoing paragraph. 

 We also know that silver invariably presents traces of gold, 

 wherefore a natural affinity between these two metals is ob- 

 served throughout the world. Gold is generally associated 

 with lead, and the sulphuret of lead in some instances is even 

 rich in gold. 



Native copper shows traces of gold. Iron may also be 

 reckoned as intimately associated, because whether in the 

 the form of pyrites, or in a decomposed state, as in the fer- 

 ruginous clay, or in the hydrous oxide of iron, or with the 

 ferruginous quartz (gossan), there are to be seen traces of 

 gold, and often in considerable quantities. Native bismuth 

 has occasionally gold adhering to it. 



In former times ' ' the electrum" of Pliny presented an 

 object of curiosity. A specimen of what was known as elec- 

 trum having been found at Schlangenberg, in Siberia, was 

 analysed by Klaproth, and proved to contain 64 gold 36 

 sdver. The said proportion corresponds with 15f carats. 

 This alloy, in times past, was looked upon as a curiosity. 

 As a great variety to the proportions of gold and silver 

 in the alloy are often met with among samples, taken even 

 from the same rocks and the same vein, a singular example 

 will here be submitted to show the varieties found in a single 

 locality, which I examined a few years ago. 



Gold from the pyrites forming veins in the Greenstone 

 porphyry, in the Supia district of South America : — 



Argentiferous Gold. 



maemato veins. Gold. Silver. 



Free gold (rarely found) in particles from 10 to 20 grains 75-00 25-00 



Ditto, seldom seen ... ... ... ... 67 "01 32-99 



From mixed ores ... ... ... ... 65 - 79 3421 



Ditto ... ... ... ... ... 56-25 43-75 



Produced by washing the residuum, pidverised sul- 

 phuret of lead ... ... ... ... 53-13 46-87 



Auriferous Silver. 



MAEMATO VEINS. 



Residuum, sulphuret of lead ... ... ... 46-87 53 -13 



Ditto ditto ... ... ... 41-67 58-33 



LA PLATA (MAEMATO VEINS). 



Mixed ores, argentiferous gold ... ... ... 56*75 43-25 



Residuum, black sulphuret of silver ... ... 37-82 62 - 18 



LOAISA (MAEMATO VEINS). 



Free gold in particles of about a dwt. ... ... 3771 62-29 



