INTRODUCTION. 



with a little quartz, and a considerable portion of mica. 

 This rock is one of the most common in the northern coun- 

 tries, where iron is singularly abundant. The eastern side of 

 the Ural mountains, for an extent of about five hundred 

 leagues, from north to south, is almost entirely composed of 

 it." He afterwards observes, that in Siberia many moun- 

 tains are composed of trap or basalt, (e containing masses or 

 veins of granite ; while the granitic mountains often contain 

 veins and masses of trap or hornblende."* This last obser- 

 vation may be universally extended $ and evinces that siderite, 

 and even trap or basaltin, is at least as ancient as granite, 

 which has hitherto been gratuitously admitted as the most 

 ancient of all the rocks. He also adds, that he has seen 

 large mountains of hornblende, or siderite, in the Altaian 

 chainf. 



In treating of iron, Patrin observes that the veins or beds 

 of iron ore, are constantly parallel to the beds of the rock, 

 which in the primitive mountains are often vertical, and 

 seem from the first to have formed an integral part of the 

 mountain which contains them; whence Buffon has called 

 them primordial mines $ whilst the veins of other metals 

 almost always intersect these beds under different angles, 

 sometimes even at right angles, and evidently appear to have 

 been of a formation posterior to that of the rock. He pro- 

 ceeds to observe that the mountain of Blagodat, on the 

 eastern side of the chain of Ural, consists of thick beds of 

 iron, separated by others of slate and a kind of trap. In 

 that of Keskanar, in the same quarter, the celebrated mag- 

 nets are mixed with a quantity of greenish siderite in small 

 spots, and extremely resplendent when the stone is polished. 

 In the Altaian chain, vertical beds of an ochry slate alternate 

 with compact beds of black iron ore. The primordial beds 

 are chiefly composed of black iron ore, often magnetic 5 the 

 strongest magnets of Siberia being those which present la- 

 minar parts, sometimes of iron, sometimes of hornblende or 



* Min. i. 120, 127. f Ib. 132. 



