156 



TRAVELS IN BRAZIL. 



incumbent upon it to a great thickness is a very 

 fine mica, approaching talc-slate, of a white, bluish- 

 yellowish-greenish, grey, or brownish colour. The 

 direction of this rock, which occurs in strata of very 

 different thickness, is on the whole from S.E. to 

 N.W., i. e. contrary to what we observed on the 

 whole in the principal mountain. The lustre of its 

 strata, which are alternately of the thickness of 

 half an inch and less, to that of a foot, but seldom 

 more, on the rifts, gives this fossil extraordinary 

 beauty, and wlien the bare parts of the mountain 

 are illumined by the sun they dazzle the eye, like 

 the castles of steel or crystal in the poem of 

 Ariosto. Large veins of a white or bluish white 

 quartz, of a glassy fracturie and lustre, traverse the 

 rock in various directions. Considerable masses 

 of it are also found scattered on the surface. In 

 many places, there appears, over the mica layers 

 of greenish or yellowish grey colour, that parti- 

 cular modification of mica-slate, which Mr. Von 

 Eschwege * has called iron mica-slate. It forms 

 layers of different thickness upon it. Brown iron- 

 stone also lies here and there, especially in loose 

 pieces, scattered on the surface. According to the 

 analogy of its appearance on the mountain of 

 Villa Rica, its layers seem to be the uppermost 

 strata in this formation ; in and upon them we ob- 

 served magnetic iron-stone crystals ; and these are 



* Journal of Brazil, Part II. Geognost. Gemalde Von Bra- 

 silien, Weim. 1822, 8vo. p. 21. 



