474 
4000 feet which owes its name “Dun Mountain” to the rusty-brown . 
(dun) colour of its surface. It consists of a very peculiar kind of 
rock , of a yellowish-green colour when recently broken , but turn- 
ing rusty -brown on the surface when decomposing. The mass of 
the rock is olivine, containing fine black grains of chromate of iron 
interspersed; it is distinguished from serpentine for which it was 
formerly taken, especially by its greater hardness, and its crystal- 
line structure. I have called it Dunite. 1 The copper-mines, how- 
ever, which are worked by an English Company (the Dun-Moun- 
tain Copper-Mining Company , residing in London) , do not lie on 
View of (lie Wooded Peak. 
1 Analysis of the Dunite, by R. Reuter (Labor, of the polyt. Institute of Vienna) 
Silica. . . . . 42.80 sp. Gr. 3.30 
Magnesia . . . 47.38 
Protoxide of iron 9.40 
Water .... 0.57 
100.15 
The Olivin-rocks are of rare occurrence. In Europe they are found principally at 
Lake Lherz in the Pyrenees, and therefore called Lherzolite. 
