6
Based on Copper Flat mine tailing samples XRD
results:
Samples consist of rock forming minerals, quartz
(SiO2), albite (NaAlSi3O8), and variable micas/mus-
covite (KAl2(AlSi3O10)(OH)2).
Samples also include clay mineral groups like
quintinite (Mg4Al2(OH)12(CO3)·3H2O), hydro-
talcite (Mg6Al2(CO3)(OH)16·4H2O), illite
((K0.65Al2[Al0.65Si3.35O10](OH)2)), and mont-
morillonite ((Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 ·
nH2O).
Geochemical Analyses
Overall, 127 samples (54 samples from Black Hawk district
mine wastes rock piles, 53 samples form Copper Flat mine
tailings and 20 samples from Magdalena district) were sub-
mitted for whole rock geochemical analyses. Figure 8 shows
a spider plot of chondrite normalized REE plot of Black
Hawk district, Copper Flat mines and Magdalena district.
The results show samples are slightly enriched in light REE
of up to 400–500 times chondritic values. Black Hawk dis-
trict mine waste samples also have higher light REE enrich-
ment as compared to the other districts.
Figure 9 shows concentrations of Black Hawk district
mine waste rock samples, Hillsboro district tailing samples,
and Magdalena district mine waste rock samples normal-
ized to average crustal abundance (Figure 9). These three
different deposits compared with the average crustal abun-
dance represent either highly enriched or depleted zones for
particular elements. For example, carbonate-hosted depos-
its (Magdalena district), represented in blue, show a strong
peak for zinc, indicating significant enrichment compared
with arsenide five-element veins (Black Hawk district in red
line.
Nickel (Ni) and cobalt (Co) are critical minerals and
Figure 10 shows correlation of 0.80 between Ni and Co
for mine wastes in the Black Hawk district, correlation of
0.79 between Ni and Co for Magdalena district and cor-
relation of 0.02 between Ni and Co for Hillsboro district
(Figure 10).
Lead (Pb) and bismuth (Bi) show correlation of 0.07
for Black Hawk district samples, correlation of 0.92 for
Magdalena district samples and correlation of 0.33 for
Hillsboro district samples (Figure 11).
Tellurium (Te) and copper (Cu) show correlation of
0.36 for Black Hawk district samples, correlation of 0.76
for Magdalena district samples and correlation of 0.20 for
Hillsboro district samples (Figure 12).
Figure 8. Chondrite-normalized REE plot of Black Hawk
district mine waste rock samples, Hillsboro district tailing
samples, and Magdalena district mine waste rock samples
Figure 9. Geochemistry of Black Hawk district mine waste
rock samples, Copper Flat mine tailing samples at Hillsboro
district, and Magdalena district mine waste rock samples
normalized to average crustal abundance
Figure 10. Ni-Co scatter plot of Black Hawk district mine
waste rock samples, Copper Flat mine tailing samples at
Hillsboro district, and Magdalena district mine waste rock
samples
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