THE IRON ORE SUPPLY OF THE SCANDINAVIAN PENINSULA. 390 
of Christiania is, on the contrary, in respect to iron ores without any 
practical importance. 
These ore provinces contain more than 90 per cent. of all the iron ore 
supply available in Scandinavia, and probably about 99 per cent. of all 
the iron ore hitherto mined in Sweden and Norway have been extracted 
from the mines of these ore provinces. 
From a geological point of view the iron ores of the Scandinavian 
Peninsula may be classified as follows :— 
1. The Ores of the Archean Crystalline Schists.—These ores belong 
to the part of the Archean rocks which are crystallised in the anamorphic 
zone and interwoven with intrusive granite. The ores occur associated 
with ortho- and para-gneisses, granulites, and dolomitised or silicified 
limestones. 
The ores of this class were long considered as sedimentary deposits 
laid down together with the over- and under-lying crystalline schists. In 
several papers from the beginning of the nineties, and later, I have pointed 
out that these ores must have been formed in the vertical or inclined 
positions they now show, and after the plication of the schists had taken 
place. I also tried to show that metasomatic processes have played a 
prominent part in the formation of these ores. I consider it most prob- 
able that the ores were formed in the deep-seated zone from thermal 
iron-bearing solutions, acting under high pressure. To what degree these 
solutions were magmatic, carrying ore substance from below, or if the 
small amount of water contained in the rock was the chief agent in col- 
lecting and concentrating the iron, is uncertain. At all events, the pro- 
cess was different from the action performed through solutions circulating 
in open channels. 
The ores of this class chiefly occur in the ore province of Central 
Sweden, but they are also represented by several great deposits in the 
ore provinces of the south coast of Norway, of Norrbotten, and of Syd- 
Varanger. 
2. The Ores of the Porphyries (also classified as Keratophyres) belong 
to a division of the Archean system younger than the old granites, but 
still plicated in pre-Cambrian time. 
The genetic connection of the ores in question with the porphyry rock 
is so manifest that it has been admitted by all who have expressed an 
opinion on the subject. But the nature of this connection is interpreted 
in very different ways. The ores have frequently been compared with 
the great iron ores of the Eastern Ural, Wissokaja Gora, Gora Blagodat, 
&c., also connected with syenitic rocks, and have, like these, been con- 
sidered as products of magmatic differentiation, But it seems not un- 
likely that these ores are also produced in a manner not differing essen- 
tially from the formation of those of the first class, that is, through the 
agency of iron-bearing aqueo-igneous solutions. The ore deposits belong- 
ing to this group are confined exclusively to the ore province of Norr-. 
botten : some of them are among the largest in the world. 
3. The Ores of the Basic Eruptive Rocks occur as differentiations 
in intrusive bodies of diabase and gabbro, forming stocks, bosses, and lac- 
colites within schists of Archean and Silurian age. The ores of this kind 
form a natural and well-defined class met with in all parts of the world. 
That these ores are genetically connected with eruptive rocks has long 
been admitted. Their nature of differentiation facies is evident from 
their structural characters, which are the same as those of the eruptive 
