152 
AMERICAN GEOLOGY. 
of nickel. The last two are rare. The ore, except when broken 
down or disintegrated, is in crystals and crystalline masses, 
with brilliant surfaces—and in this condition is very pure and 
free from sulphuret of iron. The veins lie in parallel position 
with the lamina of rock, where they can be traced to rocks of 
that class; when in serpentine or limestone the ore is apparently 
in masses, and may be removed entirely from the rock. The 
specular ore is not confined to pyrocrystalline limestone; seve¬ 
ral veins, as the Polly and Tate ores are subordinate to gneiss, 
but maintain a connection with serpentine. The Kearney and 
Parish veins are important ores, and extend for two or three 
miles in a northerly direction. 
Magnetic ore occurs at one or more localities in St. Law¬ 
rence county, in the township of Chaumont. The ore is rich', 
and being situated upon the Oswegatchie, and in a well w 7 ood- 
ed forest, will in time become a valuable location for the manu¬ 
facture of iron. 
From the foregoing remarks and illustrations, it is apparent 
that iron ores do not preserve those geological relations which 
are absolutely similar in all parts of our country. While we 
may observe, however, considerable diversity in their occur¬ 
rence, still there is such a general similarity in those respects, 
that we may avail ourselves of the use of general principles 
in conducting the necessary mining operations. This general 
similarity extends also to the conditions of the great masses 
and veins of ore which are best known, and which have been 
the most extensively worked in foreign countries, particularly 
those of Norway and Sweden. 
The annexed diagram, fig. 40, copied from a valuable article 
on the mines of Arendal,* would illustrate our own mines r of mag¬ 
netic iron. It is a ground plan; m m, masses of ore prolonged 
in the direction of the vein, but variable in width and appa¬ 
rently interrupted; gn gneiss, g limestone. This vein branches 
out into the wrnlls of the gneiss. It occupies a middle part of 
*Annales Des Mines, Tome IV, 1843. 
