COMMISSION GEOLOGIOUE - arkisto.gsf.fi

On the prospecting and geology of the Kemi chromite deposit, Finland 39
places that a drill will penetrate it without being rotated. This zone runs
very close to the ore and even touches it at many points, but at many
other points a thin layer (1-2 m) of harder rock lies between the ore and
the shear zone. The same sort of shearing has also been met with in a
deeper section, 110 meters below the surface of the earth, though it was
only a few meters thick there.
The me an content of the West End ore, taking into account the entire
ore belt excepting, however, the more scattered portion at the northeastern
end, is 21.9 % Cr 20 3 • Portions with continuously higher percentages,
Cr 20 3-content over 30 %, can be distinguished, however, in a longitudinal
direction. The most unified of them, with a thickness varying between 1.3
and 6.8 m, occurs uppermost on the hanging wall side of the ore. The highest
Cr 20 3-content analyzed in the area of the West End ore is 38.1 %, the
length of the analyzed interval being 3 . 06 m, which percentage also comes
close to the maximum values established in analyses of other ores.
NUOTTIJÄRVI ORE
About one kilometer from the West End ore toward the northeast, two
holes were drilled toward the final stage of the investigation at Nuottijärvi,
more precisely at the site of the strong geophysical indication met
with on the northeastern side of the lake. The distance between the holes
was 300 m.
The drillhole toward the southwest showed the ore to be scattered. In
the ore zone, measuring a total of some 130 m in thickness, there occurred
four different portions with a richer content of ore and approximately
equidistant from each other. Only the two situated in the middle contained
ore uniformly, whereas the other two contained ore and oreless zones in
alternation. The thicknesses of the two ore zones in the middle were 12 and
11 m respectively, with the corresponding Cr 20 3-contents being 20.1 %
and 30.5 %.
The drillhole to the northeast pierced two more uniform ore zones, between
which occurred an oreless intercalation so me 48 m thick. The first
ore is quite uniform. Its thickness is about 52 m and its Cr 20 3-content
23.9 %. In this ore the chrome-oxide content diminishes comparatively
evenly from 36.1 % on the side of the hanging wall to 12.1 % on the footwall
side.
A scattering of the ore can be observed in the lower ore zone of the
drillhole. At the end of the drillhole there occurs, however, a uniform
ore zone the thickness of which is 29 m and the Cr 20 3-content 31. 7 %.