15
Geological Survey of Finland, Bulletin 395
Geology and ore petrology of the Akanvaara and Koitelainen mafic layered intrusions and the Keivitsa-Satovaara...
analytical equipment and automation tech-
niques during the long span of the investiga-
tions. Some whole-rock compositions from
Koitelainen were determined by wet-chemical
techniques by Risto Saikkonen (GSF) but other
rocks and ores were analysed by XRF on pow-
ders or powder briquettes; the chromitite anal-
yses for Koitelainen were made on flux-fused
samples.
Se and Te were determined by graphite fur-
nace AAS after preconcentration by reductive
coprecipitation from aqua regia digestion (see
Niskavaara & Kontas, 1990). ICP-MS were
used to analyse selected samples from Keivitsa
for Ag, Ba, Bi, Cd, Hg, Mo, Rb, Se, Sr, Th, Tl,
U and V. All drill core samples from Keivitsa-
Satovaara and Akanvaara were analysed for
Au and Pd by graphite furnace AAS (Kontas et
al., 1990) and selected samples from all intru-
sions also for Os, Ir, Ru, Rh, Pt, Pd, Au and Re
by nickel sulphide-ICP-MS (Juvonen et al.,
1993, 1994); a smaller number of samples
from Keivitsa were analysed for Pt, Pd and Au
by Pb fire assay (Juvonen et al., 1994). The
CN values for PGE and Au were calculated
based on the following C1 chondrite values:
Os 761 ppb (Tredoux et al., 1989), Ir 710 ppb,
Ru 1071 ppb, Pt 1430 ppb, Pd 836 ppb (Taylor
& McLennan, 1985) and Au 152 ppb (Krähen-
bühl et al., 1973). In earlier years the acid-sol-
uble metals were determined with various dis-
solution (HCl, aqua regia) and analytical tech-
niques (OES, AAS); for Keivitsa the base met-
als (Ni, Cu, Co, Zn, Pb) were determined first
by AAS, later (from 1992 on) by ICP-AES.
Pedogeochemical till and weathered bedrock
samples taken by the Geochemistry Depart-
ment were analysed for Si, Al, Fe, Mg, Ca, Na,
K, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Pb and Ag
by OES (“quantometer”) as described by Gus-
tavsson et al. (1979); those collected by the
Exploration Department were analysed for
base metals (Cu, Ni, Co, Zn, Pb) by AAS.
Keivitsa was one of the first prospects from
which all till samples were analysed for Pd and
Au by graphite furnace AAS (Kontas et al.,
1990). H
2
O, C and S were determined by
LECO.
The following gives the number of analyses
from each study area.
Koitelainen: 91 wr analyses (XRF and wet-
chemical); 913 Pd-Au analyses; 890 Pb fire as-
says (Pt, Pd, Au); 33 nickel sulphide fire as-
says for PGE-Au-Re (of which 7 analyses by
the Canadian companies NAS and XRAL); 84
ICP; 2840 partial silicate and ore analyses
(AAS, XRF, OES); 82 XRF analyses of
chromitites; 90 analyses of Cr of high-alumi-
nous schists; 1559 metal analyses of the prod-
ucts of mineral processing tests of V-rich mag-
netite gabbro.
Keivitsa-Satovaara: 1824 whole-rock XRF
analyses; 409 Se-Te-Sb-Bi, 2263 Te, 44 trace-
element ICP-MS, 15 366 Pd-Au; 4627 PGE-
Au-Re (of which 233 by the companies NAS
and XRAL); 16 151 ICP; 2800 AAS base met-
als; 682 S (by LECO); 79 H
2
O(tot) and 696 C.
Akanvaara: 1465 whole-rock XRF analyses;
3325 Au-Pd; 261 PGE-Au-Re; 371 ICP; and
261 XRF, ICP and PGE-Au-Re analyses of
products of mineral processing tests.
Until the late 1970s electron microprobe
analyses were made by Tuula Hautala (née
Paasivirta), GSF, mainly on chromites and
magnetite, using Microscan Cambridge equip-
ment under ordinary operating conditions (ac-
celerating voltage 15 kV, probe current 20
nA). Natural chromite from the Kemi deposits,
magnetite (for V) and sphalerite (for Zn) were
used as standards. The results were corrected
with the Bence-Albee program. The next mi-
croprobe, a Jeol JXA, served until September
1993. It was used mainly for qualitative miner-
al analyses and analyses of olivine melt inclu-
sions. Raw data were corrected with ZAF pro-
cedure. Most of the analyses presented here
were made on a fully automated Cameca SX
50 probe, with four WD spectrometers. The
data were processed with the Cameca PAP
program (Pouchou & Pichoir, 1984). A PGT
EDS instrument was used for mineral identifi-
cation. In most cases natural minerals, but for