XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1459
variables which based on the “a priory” classified skarn types
(e.g., end members) are then used to predict the skarn min-
eralogy of rock samples for which only geochemical data is
available. Initially, PCA and Balances were used.
The skarn types were established based on the TIMA-X
mineralogical data using PCA, balances (Figure 3) and ter-
nary plots. The data suggests 3 main skarn types depicted
by their dominant mineralogy: Epidote skarn (Qtz – Ep
– Kfs – Pl), Magnesian skarn (Amph – Serp – Dol – Cc)
and Calcic skarn (Gt – Px – Woll). These three groups
are roughly equivalent to that earlier classified for the
Rosemont Pit (Ordóñez-Calderón et al., 2017). A fourth
group overlaps with the skarn types above reflecting mixed
background lithologies. Of the 841 samples collected for
mineralogical and metallurgical testing, a suite of 228
samples includes the relevant mineral combinations used
to group the skarn types (Epidote skarn =Qtz – Ep –
Kfs – Pl Magnesian skarn =Amph – Serp – Dol – Cc
Calcic skarn =Gt – Px – Woll). Major elements used in
the discriminant function analysis include Al, Ca, Fe, K,
and Na. Statistical data (eigenvalues) indicate that the first
two discriminant functions account for about 96% of the
total dataset variability (DF1=83% and DF2=13%), and
thus can be considered good discriminants (Figure 4). DF2
separates mainly the calcic and magnesian skarns. It can
be seen that the discrimination between a priory defined
skarn types displays good separation (Figure 4). Some
degree overlap is evident because the skarn types are not
pure end-members containing volumetrically lesser propor-
tions of the various minerals assigned to each of the skarn
types. This overlap is more obvious for the epidote skarn
and background alteration sample (Figure 4). The degree
Table 4. Liberation and association of Cu sulphides from the TIMA-X analysis
Cu Sulphides/Association Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10
Pure Cu Sulphides 23.8 23.2 15.6 11.6 17.1 27.3 33.2 44.5 39.2 47.6
Free Cu Sulphides 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Lib Cu Sulphides 18.1 11.2 17.2 30.1 17.1 14.2 14.6 16.2 17.1 15.7
CuS:2nd Cu-Silicates-Oxides 3.2 2.4 12.0 13.1 2.3 3.6 3.9 5.6 2.6 4.0
CuS:Copper Wad 0.0 0.1 0.0 0.1 0.3 0.1 0.1 0.1 0.2 0.0
CuS:Fe-Sulphides 2.1 0.8 0.0 0.6 3.9 6.8 7.9 0.9 4.0 0.1
CuS:Quartz/Feldspars 4.9 0.2 0.1 2.6 3.9 0.2 0.2 5.3 3.9 0.3
CuS:Opx/Grt/Amph/Ep 0.0 5.4 4.2 0.0 0.1 3.6 2.2 0.1 0.2 6.0
CuS:Biotite/Chlorite 0.2 0.5 0.0 0.0 0.1 0.1 0.7 0.5 0.5 0.0
CuS:Talc/Serpentine 0.0 0.6 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.2
CuS:Muscovite/Clays 0.4 0.0 0.2 0.2 0.4 0.0 0.0 0.7 0.7 0.2
CuS:Fe-(Ti)-(Mn)-Oxides 16.8 3.0 5.7 7.3 9.1 6.4 12.0 10.0 3.7 9.8
CuS:Carbonates 0.2 1.3 1.5 0.0 0.0 0.4 0.5 0.6 0.3 1.2
CuS:Other 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0
Complex 30.2 51.4 43.2 34.4 45.7 37.1 24.7 15.5 27.5 14.9
Total 100 100 100 100 100 100 100 100 100 100
Liberated 41.8 34.4 32.8 41.7 34.2 41.5 47.9 60.7 56.3 63.3
Opx: pyroxenes, Grt garnets Amph: amphibole Ep: epidote
Table 5. P80 Size (μm) of selected minerals from the TIMA-X analysis
Mineral/Sample Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10
Chalcopyrite 89 48 96 37 35 45 56 49 40 45
Chalcocite 11 28 25 181 53 38 12 34 7 10
Bornite 17 29 93 71 14 29 20 10 12 17
Malachite -5 6 13 11 17 10 -15 16
Chrysocolla 11 23 166 14 14 18 10 11 16 10
Cu-goethite 58 94 183 179 104 83 58 76 85 81
Pitch Copper Wad 8 32 71 5 -77 18 15 33 14
Cu-Chlorite 217 24 11 20 18 15 13 14 16 10
Fe-Sulphides 302 236 178 159 223 263 196 156 249 176
Quartz/ Feldspars 246 130 151 303 235 104 104 150 148 169
Opx/Grt/ Amph/Ep 33 112 219 321 50 204 78 33 49 141
Biotite/ Chlorite 66 80 25 36 46 29 55 56 23 196
Fe-(Ti)-(Mn)-Oxides 121 49 181 85 110 54 107 99 26 139
Carbonates 72 91 168 46 35 54 16 94 32 97
Particle 244 139 217 292 230 227 167 143 161 166
variables which based on the “a priory” classified skarn types
(e.g., end members) are then used to predict the skarn min-
eralogy of rock samples for which only geochemical data is
available. Initially, PCA and Balances were used.
The skarn types were established based on the TIMA-X
mineralogical data using PCA, balances (Figure 3) and ter-
nary plots. The data suggests 3 main skarn types depicted
by their dominant mineralogy: Epidote skarn (Qtz – Ep
– Kfs – Pl), Magnesian skarn (Amph – Serp – Dol – Cc)
and Calcic skarn (Gt – Px – Woll). These three groups
are roughly equivalent to that earlier classified for the
Rosemont Pit (Ordóñez-Calderón et al., 2017). A fourth
group overlaps with the skarn types above reflecting mixed
background lithologies. Of the 841 samples collected for
mineralogical and metallurgical testing, a suite of 228
samples includes the relevant mineral combinations used
to group the skarn types (Epidote skarn =Qtz – Ep –
Kfs – Pl Magnesian skarn =Amph – Serp – Dol – Cc
Calcic skarn =Gt – Px – Woll). Major elements used in
the discriminant function analysis include Al, Ca, Fe, K,
and Na. Statistical data (eigenvalues) indicate that the first
two discriminant functions account for about 96% of the
total dataset variability (DF1=83% and DF2=13%), and
thus can be considered good discriminants (Figure 4). DF2
separates mainly the calcic and magnesian skarns. It can
be seen that the discrimination between a priory defined
skarn types displays good separation (Figure 4). Some
degree overlap is evident because the skarn types are not
pure end-members containing volumetrically lesser propor-
tions of the various minerals assigned to each of the skarn
types. This overlap is more obvious for the epidote skarn
and background alteration sample (Figure 4). The degree
Table 4. Liberation and association of Cu sulphides from the TIMA-X analysis
Cu Sulphides/Association Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10
Pure Cu Sulphides 23.8 23.2 15.6 11.6 17.1 27.3 33.2 44.5 39.2 47.6
Free Cu Sulphides 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Lib Cu Sulphides 18.1 11.2 17.2 30.1 17.1 14.2 14.6 16.2 17.1 15.7
CuS:2nd Cu-Silicates-Oxides 3.2 2.4 12.0 13.1 2.3 3.6 3.9 5.6 2.6 4.0
CuS:Copper Wad 0.0 0.1 0.0 0.1 0.3 0.1 0.1 0.1 0.2 0.0
CuS:Fe-Sulphides 2.1 0.8 0.0 0.6 3.9 6.8 7.9 0.9 4.0 0.1
CuS:Quartz/Feldspars 4.9 0.2 0.1 2.6 3.9 0.2 0.2 5.3 3.9 0.3
CuS:Opx/Grt/Amph/Ep 0.0 5.4 4.2 0.0 0.1 3.6 2.2 0.1 0.2 6.0
CuS:Biotite/Chlorite 0.2 0.5 0.0 0.0 0.1 0.1 0.7 0.5 0.5 0.0
CuS:Talc/Serpentine 0.0 0.6 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.2
CuS:Muscovite/Clays 0.4 0.0 0.2 0.2 0.4 0.0 0.0 0.7 0.7 0.2
CuS:Fe-(Ti)-(Mn)-Oxides 16.8 3.0 5.7 7.3 9.1 6.4 12.0 10.0 3.7 9.8
CuS:Carbonates 0.2 1.3 1.5 0.0 0.0 0.4 0.5 0.6 0.3 1.2
CuS:Other 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0
Complex 30.2 51.4 43.2 34.4 45.7 37.1 24.7 15.5 27.5 14.9
Total 100 100 100 100 100 100 100 100 100 100
Liberated 41.8 34.4 32.8 41.7 34.2 41.5 47.9 60.7 56.3 63.3
Opx: pyroxenes, Grt garnets Amph: amphibole Ep: epidote
Table 5. P80 Size (μm) of selected minerals from the TIMA-X analysis
Mineral/Sample Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10
Chalcopyrite 89 48 96 37 35 45 56 49 40 45
Chalcocite 11 28 25 181 53 38 12 34 7 10
Bornite 17 29 93 71 14 29 20 10 12 17
Malachite -5 6 13 11 17 10 -15 16
Chrysocolla 11 23 166 14 14 18 10 11 16 10
Cu-goethite 58 94 183 179 104 83 58 76 85 81
Pitch Copper Wad 8 32 71 5 -77 18 15 33 14
Cu-Chlorite 217 24 11 20 18 15 13 14 16 10
Fe-Sulphides 302 236 178 159 223 263 196 156 249 176
Quartz/ Feldspars 246 130 151 303 235 104 104 150 148 169
Opx/Grt/ Amph/Ep 33 112 219 321 50 204 78 33 49 141
Biotite/ Chlorite 66 80 25 36 46 29 55 56 23 196
Fe-(Ti)-(Mn)-Oxides 121 49 181 85 110 54 107 99 26 139
Carbonates 72 91 168 46 35 54 16 94 32 97
Particle 244 139 217 292 230 227 167 143 161 166