Full resolution (JPEG) - On this page / på denna sida - Second part - IX. Mining Industry and Metal Production - 1. The Iron Mines (together with information regarding other mines). By the late Prof. O. G. Nordenström
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THE IRON MINES.
687
the central part of this district are situated the mines of Norberg,
ßisp-berg, Grängesberg, Riddarhyttan, Striberg, Stripa, and a large number
of other important iron ore fields. Furthest to the west, there are the
mines of Persberg, Nordmarken, Taberg (in Vermland), and Långban.
North of this ore-zone, there occur in several places ores of different
kinds, but the most important of these are situated in the neighbourhood
of the arctic circle, or in the northernmost part of Norrland. Here we
find ore-deposits at Gellivare, Kirunavara, Luossavara, Svappavara, and
Ruotivare, several of which, with respect to their length, thickness,
and percentage of iron, are the most prominent iron ores in Sweden;
the whole complex can be regarded as the thickest and richest among
the iron ores of the world. Thus the horizontal section of the
ore-deposit at Kirunavara-Luossavara has an area of 500,000 square meters.
The same section of the ores at Gellivare amounts to 200,000 square
meters. At Ruotivare the area of ore is estimated at 300,000 square
meters, and at Svappavara at 50,000 square meters. On account of the
lack of communications, however, only the Gellivare ore-field has
hitherto been worked, but Kirunavara and Luossavara also have now
begun to be worked since the Gellivare-Luleå railway has this year
(1903) been extended to the port of Narvik in Norway, which is free
from ice the year round.
As a contributing cause for these ores not having been worked on
a larger scale before, we may mention, besides the lack of
communications, in some cases their great percentage of phosphorus (Gellivare,
Kirunavara), in others, the great percentage of titanium (Ruotivare).
All the aforesaid Swedish Iron ores belong to the so-called mountain
ores, and are for the most part magnetic ores; only a comparatively
small portion consists of blood-stone (hæmatite), or of a mixture of
magnetite and hæmatite. In 1902, the production of magnetite amounted
to 2,615,533 tons, while the production of hæmatite amounted to 280,675
tons. Thus, during the aforesaid year, 90*8 % of magnetite, and only
9-7 % of hæmatite were mined.
The iron ores contain, besides the ore-minerals, a large number of other
minerals called »skarn» (gangues), appearing partly in larger or smaller
quantities, and partly in more or less intimate mixture with the ore-mineral, and
therefore contributing to give the ore a certain character. Among others, quartz is
an ordinary constituent, especially in hæmatite ores. Furthermore, we find
feldspar, chlorite, talc, pyroxene, amphibole, epidote, garnet, and apatite, several
of which are contained both in the magnetite and the hæmatite ores.
Certain iron ores are characterized by their richness in lime. They are
called in practice >blandstenar> (fluxing-stones). On the other hand, the ore
whose skarn or gangue is principally composed of pyroxene, amphibole, garnet, etc.,
can be used alone, without the admixture of other ores in making pig iron, and
are therefore called >engående* {self-fluxing). Finally, we have in the quartzy
iron ores a third class, the *torrstenar» (dry stones).
Based only on the variations in the chemical and mineralogical composition
of the ore-mineral and the minerals which accompany it, we may make the fol-
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