218 Professor Hoffmann on the Geological 
of about 80 geographical miles in length, viz. from about 14 
German miles north of Boguslawsk to near Miask, between, 
54° and 60° N. L., and the gold has apparently been derived 
from the disintegration of auriferous iron pyrites* contained in 
rocks rich in felsparand quartz, just as itis found existing in the 
granite veins of the mines of Beresovsk near Katharinenburg. 
This destruction can very well be fixed to have taken place in 
the latter part of the diluvial period; for the teeth and bones of 
the species of elephant destroyed during the last revolution were 
met with in the auriferous sand. The occurrence of platina, 
on the other hand, was confined, as it is in the Cordilleras of 
Choco, to the west side of the mountain chain. Masses have 
been found of a previously unheard of size, for Humboldt 
brought back one weighing 3 pounds 63 loth,t and afterwards 
a much larger one was discovered, weighing 103 Russian, or 
9.3 Prussian pounds. The chief locality is a marshy plateau 
(called Martian) near Nischne-Tagilsk, about 1800 feet above 
the level of the sea. 
For a long time, the original occurrence of. platina in fixed 
rocks was unknown ; the notice published by Von Engelhardt 
of its being found in a greenstone was not confirmed. Now 
we know, from the labours of Gustav Rose, that platina is met 
with in grains embedded in chromate of iron; and as the 
latter is generally accompanied by serpentine, of which large 
masses present themselves in the neighbourhood, it was probable 
that the serpentine was actually the matrix of the platina; and 
this has more recently been confirmed by direct observa- 
tion.t 
All the repositories of platina are poor in gold, but still 
the latter does occur in them, though in small quantity. 
Guided by the analogy with the phenomena presented in 
America, Humboldt was the cause of the discovery of dia- 
monds in these remarkable alluvial deposits. They were first 
found in July 1829, on the western declivity of the Ural, 
* Jameson’s Journal, vol. xiii. p. 189. 
+ The Prussian pound is equal to 1.25 lb. Troy, and the loth is equal to 
half an ounce. 
t Poggendorft’s Annalen, xxxi. p. 673, and Jameson’s Journal, vol. xviii. 
p: 366. 
