CHARACTER OF THE METALLIFEROUS VEINS. 
153 
o 
bio 
i 
the fissure, a fact which is quite constant in our own mines. A 
vertical section of the mines of 
Arendal exhibits similar arrange¬ 
ments to the mines of the Appala¬ 
chian range. Indeed, the pheno¬ 
mena are so constant that only a 
few illustrations are required to 
exhibit all the most important facts 
relating to the veins of magnetic 
and specular oxides of iron. The 
relations and circumstances under 
which these ores occur, seem to 
point to their igneous origin. In 
numerous instances minerals of con¬ 
tact are developed, such as garnet, 
hornblende, epidote, &c. In this 
respect the action of these ores re¬ 
sembles that of other pyrocrystal- 
line rocks. Garnet and epidote ap¬ 
pear to be the most common mine¬ 
rals which are developed under cir¬ 
cumstances similar to those under 
consideration. Of the two, epidote 
is the most common: it accompa¬ 
nies the numerous varieties of por¬ 
phyries, appearing in different 
stages of development, from a mere yellowish coloring of the 
rock in patches, to perfect nests of crystals. The slaty rocks of 
sedimentary origin, frequently furnish this mineral in all the 
different stages referred to. In the case of garnet, its develop¬ 
ment usually takes place contiguous to the mass of igneous 
matter, while epidote is found more extensively and widely 
diffused in the rock. 
20 
<D 
G 
Jh 
0 
G 
c3 
CD 
G 
CD 
2 
G 
O 
w 
c/T 
m 
*3 
G 
0 
bo 
«r 
’3 
G 
0 
£ 
bo 
of 
o 
o 
cz> 
<D 
CO 
m 
ccJ 
