120 | Scientific Intelligence. 
micaceous sandstone having the aspect of itacolumite, repose directly 
on transition rocks, and contain diamonds between the flakes of mi- 
ca, just as garnets occur in mica shist.* Mr. Murchison concludes that 
these precious stones were originally formed in different parts of the 
world, in secondary deposits not more ancient than those which con- 
stitute the flanks of the Ural chain. 
7. Minerals of the Miask ; (Murchison’s Russia, 437.)—Mr. Mur- 
chison informs us that the rich mineralogical treasures from the Miask 
region in the Urals, and described by M. G. Rose in his work on the 
Uralian minerals, are all found either in beds, veins, or nests of the 
granitic ridge of the Ilmen. Some of these are, zircon, black mica in 
large plates, green feldspar in enormous crystals, albite, elzolite, s0- 
dalite, cancrinite, apatite, ilmenite, pyrochlore, monazite, hornblende, 
beryl, topaz, garnet, &c. Masses of the rock with which some of the 
above minerals were associated, and which dip south-west from the sides © 
of the greater IIlmen, and appeared to be nething more than flag-like 
stratified granite, forming the external coating of the hill, have, under 
_ the critical examination of M. Rose, been distinguished by the new 
name of ** Miascite”—a rock in which in addition to white feldspar and 
black mica, the place of quartz is taken by elzlite. All these rocks 
are considered as of plutonic origin. On the eastern flank of the Ural- 
taw, chromate of iron is abundantly found, not less than 20,000 poods 
being transported. annually to Moscow from one spot, dependent on the 
Polakofsk ae acai as s elsewhere, its associates are erpeute 
8. Huge mass of green Malachite; ; (Ib. ore the copper ground of 
Nijny Tagilsk, at the chief Zavod of the Demidoff family, a mass of 
green carbonate of copper has lately been disclosed, of unparalleled size. 
It occurs at a depth of 280 feet, and its base had not been found at the 
time of Mr. Murchison’s visit, only a part of its summit and sides had 
been cleared from the matrix. The summit alone has a width of about 
9 feet and a length of about 18 feet, an enormous botryoidal mass being 
exposed beneath. The whole of the surface which had been exposed, 
was calculated to contain upwards of half a million pounds of pure 
and solid malachite. 
9. Gold and Platina of the Ural and Siberia; (Mr. Murchison’s 
Russia and the Ural.)—The available deposits of the precious metals in 
Russia are all of them diluvial sands and coarse gravel, and these are 
found only on the eastern slope, or Asiatic flank of the Ural mountains, 
and — ares atest level portions of eastern Siberia. The geological 
(8253 le ee 
e Fae de l’Acad. de Bruxelles, 184 1841, tome viil, p. 330. 
A pood is about + 36 Ibs. English, 
