MATRIX OF THE URALIAN DIAMONDS. 
481 
in the cabinet of Prince Butera) were detected in the detritus upon the banks of 
the Adolfski rivulet, at the time when the alluvium was there worked for gold. The 
operations being no longer carried on in that spot, — the quantity of gold being too 
small to repay the cost, — no more diamonds can have been detected. 
Judging from the mineral character of the Uralian rocks, Baron Humboldt had 
even before his visit to Siberia foretold, that diamonds would be found in the Ural 
as in other countries which contain platinum and palladium ; and whilst he was en- 
gaged in his journey to the Altai, the discovery at Chrestovodsvisgensk was made. 
Since that period Colonel Helmersen has shown, that diamonds have been found 
(though in a rare specimen or two) at three other points along the Ural chain 1 . 
As the existence, therefore, of diamonds in the Ural cannot be disputed, it is 
gratifying to know, that quartzose micaceous schist, identical with the diamond- 
bearing Itacolumite of the Brazils, really occurs in the portion of the Ural adjacent 
to those mines, and in a tract from whence the drainage of the Koiva and Polu- 
daska streamlets descend. We are indebted to Colonel Helmersen for this dis- 
covery, from which, as well as from his finding the same itacolumite in various 
parts of the Ural, he infers that it has been the real site of the diamonds 2 . With 
the precise geological age of the itacolumite of the Brazils we are unacquainted, 
though, like that of the Ural, it is evidently a metamorphic rock. In the former 
country it has been described by Eschwege as the chief seat of the diamonds, and 
all the rivulets in which they most abound flow from mountains composed of it. 
In M. Claussen’s description of a portion of the province of Mina’s Geraes (Moun- 
tain of Grammagoa), we are assured, that powerful and slightly inclined bands of 
soft micaceous sandstone, having occasionally the aspect of itacolumite, repose di- 
rectly on transition rocks, and contain diamonds between the flakes of mica, just as 
garnets occur in mica schist 3 . Whether this sandstone or psammite, as M. Claussen 
supposes 4 , has been metamorphosed into the crystalline micaceous schist called 
itacolumite (by no means improbable), it is not for us to determine; but as dia- 
monds have been found, in exactly similar sandstones and grits, in Hindostan 5 , there 
1 Ekaterinburg, Kushvinsk and Vercli- Uralsk. Baron Humboldt and M. Rose were prevented from 
visiting Chrestovodsvisgensk. 
2 Reise nach dem Ural, 2 Abtb. p. 202. 
3 Bulletin de l’Acad. de Bruxelles, 1841, tom. viii. p. 330. A Brazilian specimen of itacolumite in the 
Imperial Museum of the School of Mines contains two diamonds. 
4 Geogn. Gemiilde von Brasilien, p. 38 ; and Pluto Brasiliensis, p. 424. 
3 See also Mineral. Report on tlie districts of Nellore, Cuddapah and Guntoor, by Lieut. Quchterlony : 
