ENVIRONS OF NIJNY TAGILSK. 
377 
(see Comptes Rendus de l’lnstitut, October 1844), M. Le Play states in the most unambiguous manner, 
that all these magnetic iron ores are of igneous origin, thereby confirming the view applied to Mount 
Blagodat by Colonel Helmersen, to whose observations we shall refer in the next chapter, M. Le Play 
shows, that as great accumulations of this ore are often essentially composed of felspar and hornblende 
and traverse other rocks, they must be considered igneously-formed masses, which, where the above- 
mentioned materials diminish and the magnetic iron prevails, constitute (particularly when half-decom- 
posed) the productive mines of the Russians. The observations of so good an authority as M. Le Play, 
who has extensively studied the position of magnetic iron ore (fer oxydule) in Spain, and who has found 
this ore to be more or less disseminated in the very body of many of the igneous rocks of the Ural, is of 
great value in the decision of this question. 
