438 PROCEEDINGS OF THE ACADEMY OF [1897. 



trict contains are found in the upper course of the rivers Kotchkara, 

 Tschornaia, Osseika, Kamenka and Sanarka. The exploitation of 

 gold began in 1844, when the placers in the southern part of the 

 region Kamenka and Sanarka were discovered. Later these placers 

 became famous on account of the precious minerals, Cyanite, Beryl, 

 Rose Topaz, Amethyst, Euclase, Ruby, Corundum etc., which occur 

 with the gold. The first gold in primitive rock in place was dis- 

 covered in 1863. 6 



The auriferous region lies in the middle of a large granite zone 

 running north and south. The gneisso-granites strike approximately 

 east and west, but have been broken through in a direction per- 

 pendicular to this, as is shown in numerous more or less parallel 

 cracks and faults. The faults have in their turn caused the enclo- 

 sure as veins of masses of granite transformed by dynamo-meta- 

 morphic action to a dark greenish gray rock generally schistose, 

 and composed of very finely crushed masses of Orthose, Plagioclase, 

 Quartz and Mica, with secondary elements, Biotite, Amphibole (in 

 certain veins), Chlorite, Talc, Calcite, Pyrite, etc. The country rocks 

 are a granite called berezite with Feldspar partially or entirely 

 transformed to Quartz and Muscovite. The thickness of the ex- 

 ploited veins varies between O05 m. and 2 m. The veins consist of 

 gray or green opaque Quartz, in which are inclusions of little veins 

 of Chalcedony in very variable quantities (here and there of Calcite 

 and Chlorite), but filling the whole crack. The Chalcedony is repre- 

 sented principally by Mispickel, Pyrite mixed with Chalcopyrite, 

 Stibine and Galena. 



Over the greater part of the mining area the primitive rock is 

 disintegrated on the surface to a depth of 20 to 50 meters. The granite 

 is transformed to a pinkish-white clay, unctuous to the touch. The 

 Quartz becomes spongy, and contains the products of the oxidation of 

 the Chalcedonies, Ochers, sometimes oxides of manganese and 

 copper, here and there Pharmacosiderite and Arseniosiderite, also 

 haloid silver minerals with the appearance of Embolite Ag (CI Br). 

 The gold content is 5 to 13 grams per tonne. The veins are richer 

 at the top, although the gold is more equally distributed in the 

 lower parts. The gold augments proportionally to the amount 

 of mispickel, and contains about 30 p. c. Ag. The different locali- 

 ties of ore resemble each other closely. Up to the present time that 



6 The information as to this region is taken from Wyssotsky's description in 

 L. G. VI. 



