TRAVELS IN BRAZIL. 



187 



the most abundant in this formation, and either 

 in very small grains and crystals nidulating in the 

 layers of clay and lithomarge, or as a coating on 

 brown iron-stone, or embedded in it in folia. 

 This formation is prevalent, not only here and in 

 general in Minas Geraes, where they pretend that 

 diamonds have been found in it*, but also occurs in 

 several parts of the capitanias of S. Paulo, Goyaz, 

 and Bahia, where it is everywhere supposed to 

 contain gold. 



Below this iron-stone flotz lies, in most mines 

 of the Morro de Villa Rica, that modification of 

 the mica-slate which t Mr. Von Eschwege calls 

 iron mica-slate. It is a mica-slate in which the 

 mica is replaced next to the abovementioned layer 

 of iron-stone, by brown iron-stone, but otherwise 

 entirely by specular iron-ore. This kind of rock 

 is found here^ as in many places in Minas, in great 

 varieties of colour, compactness, and gravity. It 

 is most frequently steel-grey in old fractural sur- 

 face, sometimes yellowish brown or brick-coloured, 

 according to the degree of oxydation of the metal. 

 Here and there, when it has a considerable quan- 



* The piece of an iron-stone breccia, in which diamonds are 

 imbedded, and which Link (Travels in Portugal, 1801, vol. i. 

 page 248.) saw in the collection of the Marquis d'Angeja, 

 and which is now in the possession of Mr. Heuland, in Lon- 

 don, as well as some similar pieces found in the Sert^o des 

 Rio de S. Francisco, mentioned by V. Eschwege (Geognos- 

 tisches Gemalde von Brasilien, p. 43.), belong to this formation. 



f See Note 4. page 201. 



