ECONOMICAL GEOLOGY. 
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other outcrops, or rather ranges of outcrops, it needs only to re mention, 
are two; one on the lower French Broad, in Madison county, and the 
other across Cherokee and a part of Macon, along the course of Yalley 
River mainly. 
Analyses of some of the Triassic limestones of Orange show a percent- 
age of 60 to 90 of lime eorbonate, and similar beds are found in Chatham 
and Moore, some of them giving from 40 to 75 per cent, of the carbonates 
of lime and magnesia. 
An examination of certain calcareous concretion, found on the farm of 
W m. Alston, Warren county, shows the following composition : 
Silica, 0.37 
Alumina and Oxide of Iron, 2.17 
Lime, 41.32 
Magnesia, 0.90 
Potash, 0.31 
Soda,.. 0.32 
Carbonic Acid, 33.46 
Organic Matter, 0.27 
Such concretions are common among the clays resulting from the de- 
composition of the dolerytic traps, and of the amphibolitic rocks of the 
Archaean series in this state ; and they are sometimes sufficiently abund- 
ant to constitute a resource for lime, in cases where limestone is inacces- 
sible. They are of notably frequent occurrence about Shiloh Church in 
Granville, in the rich earths of the Grassy Creek and Spewmarrow Creek, 
and common in the central (Greensboro) granite belt. 
SECTION II— METALLIC ORES. 
IKON ORES. 
The ores of iron are very widely distributed in this state, their occur- 
rence being not only co-extensive with the area of the Archaean (or Azoic) 
rocks, but extending over a part of the Mesozoic, and even into the Quat- 
ernary. And these occurrences include all the principal kinds of ore, 
Magnetite, Hematite, Limonite and Siderite, and most of their varieties 
and modifications. But as many of these forms occur in association or 
close proximity, it will avoid confusion to consider them by districts, — to 
group them geographically. We begin with the most easterly occur- 
rences. But for the benefit of those who are not familiar with the min- 
eralogy of the subject, and who may not have access to authorities, it may 
