: gv - ve - ‘ al 
OF SOUTH CAROLINA. 17 
excepting where it is disseminated in the slates in minute particles. I do not speak of deposit 
mines, derived from veins, where the gold is found in detached particles, intermingled with rounded 
pebbles and angular rocks of every description. 
Silver is found in all the metamorphic rocks, as well as in those of the carboniferous formation.— 
It is very frequently associated with lead. In North Carolina it is found with lead, zine and gold, 
in talcose slate. 
Copper has a wide range, and is found from the granite to the new red sandstone inclusive. 
Lead is also extensively distributed. The Davidson mine, in North Carolina, is in the talcose 
slates; but the lead mines of the West are situated in the limestone of the Silurian system. ‘The 
carboniferous or mountain limestone is also a great repository of this valuable mineral, The prin- 
cipal form in which it occurs is that of galena. 
Mercury is, for the most part, confined to the secondary rocks, although it sometimes occurs in 
older formations. 
Tin belongs to primary rocks: it is generally disseminated through the rocks and rarely occurs 
in regular veins. 
Zinc is found in the form of blende in granitic and metamorphic rocks ; and in the paleozoic 
rocks, in that of colamine. 
Antimony occurs in primary and paleozoic rocks. 
Cobalt, Bismuth, and Nickel are found in granite, metamorphic and upper paleozoic rocks. 
Manganese.—The principal deposits of this mineral are confined to the metamorphic rocks. 
RECAPITULATION. 
The conclusions of Geologists respecting the unstratified and stratified primary rocks, may be 
briefly expressed. 
1. That the lowest rocks in the earth’s crust, of which we have any knowledge, are crystalline, 
unstratified, and composed of a few simple minerals. They were called primary, because it was 
once thought that they were the oldest or first formed rocks. More recent investigations have 
shown that although they form the base or foundation of all the other rocks, they have been 
formed at various and comparatively recent periods. 
2. These rocks admit of a very natural division into granitic and basaltic rocks. The former 
are highly erystalline, and although they are often protruded into the superincumbent rocks, they 
compose the platform on which all the others rest. ‘The basaltic rocks, on the contrary, are gene- 
rally found filling the fissures and rents of other rocks, or spread out on the surface, as if by over- 
flowing. They frequently assume a columnar structure, often of striking regularity. 
3. That the primary rocks are of igneous origin is proved by the fact that they have been 
imitated or re-produced by fusing rocks and allowing them to cool slowly, and that they Rave 
produced effects upon other rocks that can only be explained by the supposition of contact with 
intensely heated matter. 
4. The increase of temperature, which is about 1° in 45 feet, as we descend below the surface of 
the earth, thermal springs, and voleanic action, all point to a central, or at least a source of heat 
beneath the earth’s crust of immense extent. 
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