222 : Scientific Intelligence. 
The second division of the quartzites is characterized by the 
substitution of the green matter by micaceous iron and often by 
the disappearance of the quartz; these pass to beds of iron ore 
known by the name of étabirite. The beds of itabirite attain in 
places the thickness of more than 200 metres and by the abundance 
and purity of the mineral and the facility of extraction constitute 
the richest iron ore deposits of the world. The iron is often accom- 
panied by oxide of manganese which in places enters in a propor- 
tion as high as 9 per cent, or more. 
n the friable itabirites gold is often found disposed in a 
manner which seems to be peculiar to Brazil, The gold appears 
to be irregular but it Lt hit tos that the rich lines have, like veins, 
i t 
| 
he schistose rocks are of very variable characters, and when 
fully studied, either from a geological or mineralogical point of 
; “1 . 
view, will fall into several divisions, ey are generally shales 
schists. The schists may be divided into two groups with 
reference to their relations to the itabirites, namely, those below 
the itabirites characterized by brilliant mica-like scales, extreme 
softness, and a relatively small development of the schistose 
structure, and those superior to the itabirites characterized by 4 
greater predominance of the argillaceous character and of the 
schistose structure. 
h 
farther south and the rock becomes crystalline, passing to mica 
The lline 
ryls, ete. ; 
n the series of schists the gold-bearing veins are less numerous 
than in the other groups described, and are of inconstant richness. 
In places gold also appears distributed in the rock in a manner 
analogous to that in the itabirites but this only occurs in the pa 
contiguous to the latter rock. The group of schists 18 
* These are evidently hydromica schists,- -EDs. 
