XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1455
Cu, 0.10% sulfuric acid soluble Cu, 117 g/t Mo, 0.02 g/t
Au and 4.22 g/t Ag. The mineralization is hosted within
a Paleozoic sequence of chemical sedimentary rocks inter-
bedded with volumetrically lesser siliciclastic lithologies,
comprising limestone, dolostone, marlstone, calcareous
siltstone, calcareous sandstone, mudstone, siltstone, and
fine-grained sandstone (Rasmussen et al., 2012). The above
sequence rests unconformably over a suite of continental
Precambrian granitoids and is intruded by a suite of miner-
alized tertiary quartz feldspar porphyry intrusive (Figure 2)
thought to represent the source of the heat and mineral-
izing fluids responsible for the widespread calc-silicate
metasomatism (Keith and Wilt, 1986). Garnet, pyroxene,
wollastonite, serpentine, epidote are the dominant calc-
silicate alteration mineral assemblages typically associated
with the various skarn facies and mineralization at copper
world (Ordóñez-Calderón et al., 2017).
The mineralization is primarily hosted within skarn
and is formed in the Paleozoic sedimentary sequence, of
which garnet-diopside-wollastonite skarns are the most
widespread type and diopside-serpentine skarn occur in
volumetrically lesser proportions. Marble and hornfels are
also present although they are weakly mineralized. Quartz
feldspar porphyries host volumetrically significant eco-
nomic mineralization in the Elgin and Broadtop Butte
deposits. Overall, mineralization occurs dominantly as
bornite-chalcopyrite-molybdenite veinlets and dissemina-
tions. Near-surface weathering and oxidation has resulted
in disseminated and fracture-controlled copper oxide min-
erals and copper carbonate minerals as well as copper wad,
most notably along the East deposit (Tavchandjian, 2023).
The Copper World deposits occur spatially associ-
ated along north trending, steeply-dipping backbone fault
system, which represent a structural contact dominated
by Precambrian granitoids to the west and the Paleozoic
chemical sedimentary lithologies to the east. Sleeves of
Precambrian granitoid lithologies structurally interleaved
with panels of Paleozoic chemical sedimentary rocks com-
monly occur along the backbone fault system (Rasmussen
et al., 2012). The Precambrian granitoids are generally non
or weakly mineralized, however it may contain some eco-
nomic mineralization where sleeves of mineralized chemi-
cal sedimentary rocks are structurally juxtaposed west of
the backbone fault.
METHODOLOGY
Samples
Samples were generated for mineralogical and metallurgi-
cal testing by randomly selecting 30–50 ft intervals of half-
core which were spatially distributed within the various
mineralized zones of the Copper World Complex. Various
composite and variability samples were studied. A total of
841 has been collected for mineralogical and metallurgical
testing. Subsets of samples are used to illustrate the results
herein.
Geochemical and Mineralogical Analysis
The mineralogical work was conducted with Tescan
Integrated Mineral Analyzer (TIMA-X) supported by
Electron Probe Micro-Analysis (EPMA), X-ray diffraction
analysis (XRD), and chemical assays by ICP-MS, Cu spe-
ciation (three acid Cu), and S by Leco. Each sample was
stage ground to a P80 of 150–300 µm. Graphite impreg-
nated polished mounts were prepared from each sample.
The TIMA-X results are based on greater than 300,000 par-
ticles from each sample.
The mode of TIMA-X analysis used for this project
was Dot Mapping (TDM). The TDM analysis mode uses a
back scattered electron (BSE) grid at a predetermined pixel
spacing to segment areas of homogenous BSE intensities
and identifies the centre of the greatest inscribed circle (like
the point spectroscopy), it then creates a grid for the X-ray
acquisition with the specified resolution spacing the same
as the BSE. The X-ray data from zones of similar BSE and
energy dispersive spectroscopy (EDS) signals are summed
to produce a single higher quality spectrum for each final
segment, which is used for the mineral identification. This
analysis mode was used to speciate and quantify the min-
eral mass%, grain size, and liberation and association of the
minerals.
Data Analysis
The mineralogical association of the studied dataset inter-
preted to be the result of hydrothermal metasomatism/
alteration and mineralization processes was broadly assessed
by principal components analysis. This type of analysis is
designed to work in real number space (i.e., -∞ to +∞)
under the assumption of multivariate normality (e.g.,
Pawlowsky-Glahn and Buccianti, 2011) and thus is not
affected by spurious correlations, in contrast to geochemi-
cal data which represent positive vectors that typically sum
to a constant (i.e., 100%). The solution to this problem
is to work with log-ratio transformations as proposed by
Aitchison (1982). The centred log-ratio (clr) transforma-
tion is obtained by dividing the concentration of each ele-
ment by the geometric mean and then taking the logarithm
of that ratio.
The variability explained by the mineral groupings
in the principal components analysis was also illustrated
by the use of balance dendrograms (cf., Egozcue and
Cu, 0.10% sulfuric acid soluble Cu, 117 g/t Mo, 0.02 g/t
Au and 4.22 g/t Ag. The mineralization is hosted within
a Paleozoic sequence of chemical sedimentary rocks inter-
bedded with volumetrically lesser siliciclastic lithologies,
comprising limestone, dolostone, marlstone, calcareous
siltstone, calcareous sandstone, mudstone, siltstone, and
fine-grained sandstone (Rasmussen et al., 2012). The above
sequence rests unconformably over a suite of continental
Precambrian granitoids and is intruded by a suite of miner-
alized tertiary quartz feldspar porphyry intrusive (Figure 2)
thought to represent the source of the heat and mineral-
izing fluids responsible for the widespread calc-silicate
metasomatism (Keith and Wilt, 1986). Garnet, pyroxene,
wollastonite, serpentine, epidote are the dominant calc-
silicate alteration mineral assemblages typically associated
with the various skarn facies and mineralization at copper
world (Ordóñez-Calderón et al., 2017).
The mineralization is primarily hosted within skarn
and is formed in the Paleozoic sedimentary sequence, of
which garnet-diopside-wollastonite skarns are the most
widespread type and diopside-serpentine skarn occur in
volumetrically lesser proportions. Marble and hornfels are
also present although they are weakly mineralized. Quartz
feldspar porphyries host volumetrically significant eco-
nomic mineralization in the Elgin and Broadtop Butte
deposits. Overall, mineralization occurs dominantly as
bornite-chalcopyrite-molybdenite veinlets and dissemina-
tions. Near-surface weathering and oxidation has resulted
in disseminated and fracture-controlled copper oxide min-
erals and copper carbonate minerals as well as copper wad,
most notably along the East deposit (Tavchandjian, 2023).
The Copper World deposits occur spatially associ-
ated along north trending, steeply-dipping backbone fault
system, which represent a structural contact dominated
by Precambrian granitoids to the west and the Paleozoic
chemical sedimentary lithologies to the east. Sleeves of
Precambrian granitoid lithologies structurally interleaved
with panels of Paleozoic chemical sedimentary rocks com-
monly occur along the backbone fault system (Rasmussen
et al., 2012). The Precambrian granitoids are generally non
or weakly mineralized, however it may contain some eco-
nomic mineralization where sleeves of mineralized chemi-
cal sedimentary rocks are structurally juxtaposed west of
the backbone fault.
METHODOLOGY
Samples
Samples were generated for mineralogical and metallurgi-
cal testing by randomly selecting 30–50 ft intervals of half-
core which were spatially distributed within the various
mineralized zones of the Copper World Complex. Various
composite and variability samples were studied. A total of
841 has been collected for mineralogical and metallurgical
testing. Subsets of samples are used to illustrate the results
herein.
Geochemical and Mineralogical Analysis
The mineralogical work was conducted with Tescan
Integrated Mineral Analyzer (TIMA-X) supported by
Electron Probe Micro-Analysis (EPMA), X-ray diffraction
analysis (XRD), and chemical assays by ICP-MS, Cu spe-
ciation (three acid Cu), and S by Leco. Each sample was
stage ground to a P80 of 150–300 µm. Graphite impreg-
nated polished mounts were prepared from each sample.
The TIMA-X results are based on greater than 300,000 par-
ticles from each sample.
The mode of TIMA-X analysis used for this project
was Dot Mapping (TDM). The TDM analysis mode uses a
back scattered electron (BSE) grid at a predetermined pixel
spacing to segment areas of homogenous BSE intensities
and identifies the centre of the greatest inscribed circle (like
the point spectroscopy), it then creates a grid for the X-ray
acquisition with the specified resolution spacing the same
as the BSE. The X-ray data from zones of similar BSE and
energy dispersive spectroscopy (EDS) signals are summed
to produce a single higher quality spectrum for each final
segment, which is used for the mineral identification. This
analysis mode was used to speciate and quantify the min-
eral mass%, grain size, and liberation and association of the
minerals.
Data Analysis
The mineralogical association of the studied dataset inter-
preted to be the result of hydrothermal metasomatism/
alteration and mineralization processes was broadly assessed
by principal components analysis. This type of analysis is
designed to work in real number space (i.e., -∞ to +∞)
under the assumption of multivariate normality (e.g.,
Pawlowsky-Glahn and Buccianti, 2011) and thus is not
affected by spurious correlations, in contrast to geochemi-
cal data which represent positive vectors that typically sum
to a constant (i.e., 100%). The solution to this problem
is to work with log-ratio transformations as proposed by
Aitchison (1982). The centred log-ratio (clr) transforma-
tion is obtained by dividing the concentration of each ele-
ment by the geometric mean and then taking the logarithm
of that ratio.
The variability explained by the mineral groupings
in the principal components analysis was also illustrated
by the use of balance dendrograms (cf., Egozcue and