954 The American Naturalist. [November, 



At Oufa, at the foot of the Ural Mountains, we entered a zone 

 of openly folded paleozoic rocks including the Devonian 

 series, the folds becoming rapidly more compressed and the 

 disturbances greater as we advanced into the mountains. At 

 Slatoust we encountered the first crystalline schists, considered 

 by Tschernyscheff our leader, on stratigraphic evidence which 

 but few of the party considered conclusive, to be metamorphic 

 Devonian. 



Within this band of schists or on its borders, is a group of 

 mineral localities which have produced many interesting and 

 beautiful specimens obtained by the efforts of many engineers 

 of the Russian Mining Bureau through a long series of years, 

 and now in large part preserved in the cabinet of the Mining 

 Academy in St. Petersburg. These minerals all appear to be 

 contact products between clay slates and limestones and mas- 

 sive eruptive rocks of the character of diorite or peridotite. 

 One of the best known and most typical of these occurrences 

 is the Achmatoff mine. Here, on a more or less chloritic 

 matrix, were found beautiful crystallizations of garnet, epi- 

 dote, pyroxene, vesuvianite, such titamium minerals as perof- 

 skite, titanite and ilmenite, zircon, apatite and various mem- 

 bers of the chlorite group. 



Passing eastward still across the Ural divide, we entered a 

 region of gneisses and granitic rocks. The day spent at 

 Miass, in the Ilmen Mountains, under the joint leadership of 

 Karpinsky and Arzruni, was replete with interest. The Ilmen 

 Mountains are a subordinate range of the Ural chain composed 

 largely of eleolite-syenite, classical under Gustav Rose's name 

 of miasclte. This rock is well exposed, is rich in a variety of 

 minerals and offers numerous interesting problems to the pet- 

 rographer. The most notable minerals here collected, chiefly 

 from the pegmatitic facies of the rock, were nepheline, can- 

 crinite and sodalite, zircon, apatite, ilmenite and biotite in 

 huge plates. In the pegmatite veins traversing the neighbor- 

 ing gneiss and granite, we saw a very different group of min- 

 erals including albite and microcline, topaz, zircon and cuclase 

 and samarskite, pyrochlor and other rare earth minerals. 



