GOLD. 147 



altitudes above the level of the sea, but as a rule they do not rise above 2,000 feet, the 

 height of the mountain chains being twice and three times greater. In the Kousnets Alatau 

 the height of the mountains is from five to six thousand feet and the gold deposits become 

 smaller and poorer as the mountain chain rises towards the south. 



The geognostic character of the gold deposits of Siberia also varies in different local- 

 ities. The gold bearing rock of the Kousnets Alatau is greenstone ; on the eastern declinity 

 of this mountain ridge the extreme slopes, down to the openings of the valleys, are composed 

 of clay slate, which higher up the current changes into metamorphic and calcareous clay slates, 

 which change into jaspers and hornblendes near their contact with the gi-anites and diorites. 



The predominating rocks of both the northern and southern parts of the Yenisei region 

 is made up of various kinds of metamorphic slates among which clay slate predominates and 

 in some instances passes into mica schist. The northern system also presents gi-auites, 

 gneisses, diorites and porphyries, which appear more rarely in the southern system. In the 

 northern system, limestones, sandstones and conglomerites are also found in places. The gold 

 bearing strata lie in various kinds of slates, near their contact with gi-anites and diorites; 

 and wherever this combination occurs gold is sure to be found. The predominating rocks in 

 the southern regions of the government of Yenisei in the spurs of the Sayansk mountains 

 are granite, cyanite, limestone and metamorphic slates. 



In the province of Yakutsk the chief rock of the gold bearing systems of the rivers 

 Olekma and Yitima is a granitic cyanite, which changes in places into a more laminated 

 structure, passing into gneiss, which imperceptibly passes into micaceous, chloritic talc and 

 clay schists. All these rocks are distinguished for their being gold bearing, especially the 

 clay schists. The general character of the rocks of the valleys of the Nerchinsk region is the 

 same, consisting as they do of granite, gneiss, cyanite, greenstone, diorite and dioritic cyanite 

 and felspar porphyries. The geological structure of the gold bearing region of the Amour 

 province, along the river Zei, is composed of micaceous and hornblend gneisses and slates. The 

 characteristic feature of the presence of gold is the passage of the one class of rocks into the other. 



The composition of the gold deposits themselves depends upon the rocks surrounding 

 them. The thickness of the deposits varies greatly, from two feet to three sagenes and more ; 

 but generally it varies between two and seven feet. The upper strata of the deposits 

 contain bones of mammoths, rhinoceros, and other extinct and existing animals. All the deposits 

 are covered by a layer of earth, known as peat. The length of the deposits varies from 

 one to fifty versts and more, sometimes with a layer of gold bearing sand, extending along 

 their entire length of sufficient thickness for profitable working. As a rule the richness of the 

 gold bearing strata varies in each deposit; the upper portion generally contains a small 

 accumulation of coarse particles of gold mixed with quartz, magnetic iron and pyrites; in 

 the middle portion the gold is finer in its particles and the sand poorer in gold, and lastly 

 ill the tail of the deposit there remains a floating gold dust which only gives traces of gold. 

 The soil of nearly all the northern portion of Eastern Siberia is perpetually frozen. The frozen 

 state of the soil and the dense forests which subsequently covered the deposits have favoured 

 the preservation of the gold in them, from the wearing and denuding action of the water. 

 Many of the Eastern Siberian gold deposits show undimbted traces of the influence of glaciers. 



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