2098 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Results from EPMA mapping (data not shown) confirmed
the major mineral phases present in each of these fractions.
Garnet fraction
QXRD analysis results for the garnet fraction indicated
the sample contained 79 wt% garnet, 9 wt% amphibole,
8 wt% epidote, 3 wt% quartz and 1 wt% mica. EPMA
mapping results are shown in Figure 4. The data indicate
the sample comprised over 81.1% (by area) garnet and with
minor amounts of, in order of relative abundance, amphi-
bole (4.6%), epidote (4.4%), Ce-allanite (3.6%) and quartz
(1.8%). Element distribution plots (not shown) indicated
the garnets varied considerably in composition although in
general, most were Fe-rich. Compared to XRD, the EPMA
analysis could identify a significant number of minor
mineral phases including biotite, ilmenite, titanate, mag-
netite, apatite, feldspar, sillimanite, and zircon, plus trace
sulphides. Only the presence of phases with abundance
1% are shown in Figure 4. For the most part, the garnet
grains exhibited a high degree of angularity and were largely
inclusion free. Where inclusions were observed, these were
dominated by quartz, amphibole, and epidote.
Figure 4. EPMA map results for the garnet fraction showing the distribution of major phases at
levels 1% by area
Quantitative EPMA results
Quantitative EPMA data was obtained on the Fe-Ti oxide
phases in the Ilmenite, Mag. mx and Non-mags fractions
and is presented in Table 3. These results were used to pre-
pare an Fe vs Ti scatter plot for these phases and this plot
is given in Figure 5. Compositions of the Fe-rich and Fe/
Ti-rich phases (from Figure 5 and Table 3) extended from
~0 wt% Ti (hematite) to ~35 wt% Ti (ilmenite), indicating
compositions ranging from stoichiometric ilmenite (~31%
Ti) to grains containing excess hematite component. Some
rutile grains were also present in the Mag. Mix and Non-
mags fractions. Textures of the ilmenite grains indicated
little or no evidence of alteration to more Ti-rich phases.
Major impurity elements in the ilmenite (Table 3) were
Mn and V. Note that the absolute amount of Mn varied
between the fractions with the Non-mags fraction contain-
ing ilmenite with the highest Mn level (and lowest Fe level).
Quantitative EPMA data was also collected for the gar-
nets in the garnet fraction (data not shown). From over 100
grains analysed, the garnets contained, on average, SiO2
(34.1–38.7 wt%), FeO (10.9–38.8 wt%), Al2O3 (20.5–
24.3 wt%), CaO (0.4–23.4 wt%), MgO (0.1–7.9 wt%)
and MnO (0.1–15.7 wt%). The compositional data were
Results from EPMA mapping (data not shown) confirmed
the major mineral phases present in each of these fractions.
Garnet fraction
QXRD analysis results for the garnet fraction indicated
the sample contained 79 wt% garnet, 9 wt% amphibole,
8 wt% epidote, 3 wt% quartz and 1 wt% mica. EPMA
mapping results are shown in Figure 4. The data indicate
the sample comprised over 81.1% (by area) garnet and with
minor amounts of, in order of relative abundance, amphi-
bole (4.6%), epidote (4.4%), Ce-allanite (3.6%) and quartz
(1.8%). Element distribution plots (not shown) indicated
the garnets varied considerably in composition although in
general, most were Fe-rich. Compared to XRD, the EPMA
analysis could identify a significant number of minor
mineral phases including biotite, ilmenite, titanate, mag-
netite, apatite, feldspar, sillimanite, and zircon, plus trace
sulphides. Only the presence of phases with abundance
1% are shown in Figure 4. For the most part, the garnet
grains exhibited a high degree of angularity and were largely
inclusion free. Where inclusions were observed, these were
dominated by quartz, amphibole, and epidote.
Figure 4. EPMA map results for the garnet fraction showing the distribution of major phases at
levels 1% by area
Quantitative EPMA results
Quantitative EPMA data was obtained on the Fe-Ti oxide
phases in the Ilmenite, Mag. mx and Non-mags fractions
and is presented in Table 3. These results were used to pre-
pare an Fe vs Ti scatter plot for these phases and this plot
is given in Figure 5. Compositions of the Fe-rich and Fe/
Ti-rich phases (from Figure 5 and Table 3) extended from
~0 wt% Ti (hematite) to ~35 wt% Ti (ilmenite), indicating
compositions ranging from stoichiometric ilmenite (~31%
Ti) to grains containing excess hematite component. Some
rutile grains were also present in the Mag. Mix and Non-
mags fractions. Textures of the ilmenite grains indicated
little or no evidence of alteration to more Ti-rich phases.
Major impurity elements in the ilmenite (Table 3) were
Mn and V. Note that the absolute amount of Mn varied
between the fractions with the Non-mags fraction contain-
ing ilmenite with the highest Mn level (and lowest Fe level).
Quantitative EPMA data was also collected for the gar-
nets in the garnet fraction (data not shown). From over 100
grains analysed, the garnets contained, on average, SiO2
(34.1–38.7 wt%), FeO (10.9–38.8 wt%), Al2O3 (20.5–
24.3 wt%), CaO (0.4–23.4 wt%), MgO (0.1–7.9 wt%)
and MnO (0.1–15.7 wt%). The compositional data were