484 PLATINUM AS WELL AS GOLD SOMETIMES DISSEMINATED. 
ore, so abundant in the gold alluvia. The platinum had formerly, it appears, been 
found, for the most part, in fragments from the weight of a zolotnik to near one 
pound, though rarer examples had occurred of pieces weighing from three to up- 
wards of eight pounds. According to Rose, the major part of the detritus asso- 
ciated with the platinum consists of serpentine, with very rare appearances of 
hypersthene or other minerals, the ground over which it has been washed being 
either chlorite schist or quartzose talc schist, the latter containing diffused epidote. 
The platiniferous alluvia on the west slope of the Ural ridge, like the gold alluvia 
on the east, has in truth been drifted down into adjacent depressions from the cul- 
minating peaks of hornblende slate, serpentine and greenstone, and is occasionally 
from ten to twelve feet thick. It differs only from the gold alluvia in being usually 
arranged in narrower masses, the breadth of one mass being eighteen to twenty four 
feet, and of another thirty to forty, and their lengths from 300 to 400 feet ; whilst 
there are many gold accumulations more than treble such length and breadth. In 
our own examination, indeed, of a heap of detritus north of Kushvinsk, from which 
platinum ore had been extracted, we could detect no sensible geological distinction 
between it and the auriferous detritus in the neighbouring valleys, since we found 
them both to be composed of various sub-angular veinstones and rocks of the adja- 
cent ridges (see p.381). By this observation, however, we by no means wish to 
imply, that the formation of platinum ore may not, in other instances, have been 
accomplished by a natural process separate from that which in most instances ela- 
borated the gold ; but we believe, that with the present amount of evidence it 
would be unsafe to attribute the origin, of either platinum or gold, exclusively to 
one mode of formation. 
We are led to make this remark from a recent publication of M. Le Play, whilst 
these sheets are passing through the press 1 . Availing himself of the light thrown 
upon this subject by the scientific researches of M. Schwetzof and the mineral 
agents of M. DemidofF, this able mineral surveyor, who, as before said, visited a part 
of the Ural Mountains since we quitted them, has come to the conclusion, that the 
platinum of Nijny Tagilsk was not formed in veins, but disseminated throughout 
the whole mass of certain crystalline rocks (gisement primitif). He founds this 
belief on having followed twenty or more courses of platiniferous alluvia up to a 
common centre, the mountain La Martiane, from which they have all been derived, 
and of whose detritus they are all composed. No quartzose veinstones occur, and 
1 Comptes Rendus a llnstitut de France, Novembre 1844. 
