GEOLOGY OF CENTRAL MINAS GERAES, BRAZIL 



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thick and of small diameter. Of the three classes of bedded ores, 

 hard massive ore and the peculiar soft powdery ore are the most 

 widespread, the latter probably being the more common of the two. 

 Laminated ore is less widespread, but generally occurs in larger 

 deposits. 



The hard ore of central Minas is of several varieties, the most 

 common of which is a slightly specular blue hematite resembling 



Fig. 12. — The Peak of Caue rising above the town of Itabira de Matto Dentro. 

 A large body of hard ore. 



some of the specular hematite ores on the Marquette range in Michi- 

 gan. Such ores occur in many places in the district. Locally there 

 are deposits consisting of coarsely specular hematite with scattered 

 crystals of martite, and with these are frequently associated ores 

 composed largely of coarse granular masses of martite, or magnetite 

 not yet completely altered to hematite. Such phases are due 

 probably to greater metamorphism and are most common in the 

 eastern part of the district. In the central and western part of the 

 district there occur a few deposits of a tough, fine-grained, almost 

 amorphous hematite, or hematite intermixed with some limonite. 



