444 PROCEEDINGS OP THE ACADEMY OF [1897. 



holocrystalline uralite on the one hand, or into compact orthose 

 on the other is here observed. The intimate correlation of the 

 combined elements of different structure and color appears in the 

 ribbon or spotted structure of the rock, offering a good example 

 of the composition of the " Schlieren." 8 The interpretation of the 

 structure by M. Tschernischew is that the metalliferous masses and 

 the accompanying rocks were formed simultaneously, and that the 

 beds of magnetite have separated themselves from the magma of 

 orthose rocks. The magnetite and accompanying rocks of Wysso- 

 kaja dip generally southeast and east, but the structure is compli- 

 cated by throws and faults to be seen on the west end of the 

 mountain. 



Brecciform rocks form the base of the series of metalliferous beds 

 ofWyssokaja. Here can also be seen the disintegrating acfion of 

 the orthose rocks, which results in the formation of thick beds of 

 white and pink clays, enveloping blocks of magnetite. The iron of 

 Wyssokaja is distinguished for its purity and excellent metallurgical 

 qualities. The magnetite is very often observed passing into martite, 

 a mineral very abundant near Taguil. 



Among the minerals of Wyssokaja are Asbolan and Rabdionite, 

 forming in places very thin deposits on the walls of fissures in the 

 Magnetite and Martite. Immediately to the south of these mines 

 occur the outcrops of a white siliceous limestone, which forms the 

 western boundary of the rocks which contain the Mednoroudiansk 

 deposits. 



The Mednoroudiansk copjier mines are situated to the south of 

 Wyssokaja-Gora, between two narrow bands of limestones enclosing 

 clays, and disintegrated porphyries and tuffs. Along the line of the 

 deposit is found a band of argillaceous limonites and clays. 



The southern part of the mine is separated from the northern by a 

 thick vein of lamprophyre oblique to the general direction of the 

 deposit. These iron minerals appear to fill a crack produced by a 

 fault irregularly bounded on the east and west. The clays of yellow 

 ocher are rich in copper oxides, and great masses of Malachite taken 



8 These passages of massive to schistoid and gneissic structure, the insensi- 

 ble transition of gabbros and gabbro-diorites by a series of intermediate phases 

 to diallage and amphibole-diallage rocks composed of only bisilicates, appear- 

 ing not only on the same outcrops, but even in the same fragment of rock, 

 carry conviction to the mind that these complicated combinations of fels- 

 pathic with non-felspathic masses which Reyer proposed to call " Schlieren," 

 exist. L. C, IX, 3. 



