7
determined by Acid Base Accounting (ABA) and Net Acid
Generation (NAG) tests.
The ABA procedure consists of two separate tests the
acid potential (AP) test and the neutralization potential
(NP) test. ABA was calculated and plotted on the ARD
classification plot for waste rock pile samples from the vari-
ous mines (Sobeck et al., 1978). The assumption is that all
C in the samples are as CaCO3 (no organic carbon) and
that the NAG pH equals the measured paste pH of the
sample. The formula used include:
AP (kg CaCO3/tonnes) =31.25 x S (%)
NP (total C) =83.3 x C (%),
NNP =NP – AP,
NPR =NP/AP
This type of geochemical analysis can be used to develop
site-specific criteria for the identification of potential acid
generating rock types. Paste pH is a simple, rapid, and inex-
pensive screening tool that indicates the presence of readily
available NP (generally from carbonate) or stored acidity.
The outcome of the test is governed by the surficial proper-
ties of the solid material being tested, and more particularly,
the extent of soluble minerals, which may provide useful
information regarding anticipated mining-influenced water
quality. For example, acidic paste pH values in combination
Figure 7. Chondrite-normalized (Taylor and McLennan, 1985) rare earth elements (REE)
for samples from mining districts and different deposit types in New Mexico. See Table 1 for
summary of districts sampled and Figure 3 for locations
Figure 8. Ni verses Co for samples from mining districts in
New Mexico. See Table 1 for summary of districts sampled
and different deposit types, and Figure 3 for locations.
Legend is in Figure 7
Figure 9. Bi verses Te for samples from mining districts
in New Mexico. See Table 1 for summary of districts and
different deposit types sampled, and Figure 3 for locations.
Legend is in Figure 7
determined by Acid Base Accounting (ABA) and Net Acid
Generation (NAG) tests.
The ABA procedure consists of two separate tests the
acid potential (AP) test and the neutralization potential
(NP) test. ABA was calculated and plotted on the ARD
classification plot for waste rock pile samples from the vari-
ous mines (Sobeck et al., 1978). The assumption is that all
C in the samples are as CaCO3 (no organic carbon) and
that the NAG pH equals the measured paste pH of the
sample. The formula used include:
AP (kg CaCO3/tonnes) =31.25 x S (%)
NP (total C) =83.3 x C (%),
NNP =NP – AP,
NPR =NP/AP
This type of geochemical analysis can be used to develop
site-specific criteria for the identification of potential acid
generating rock types. Paste pH is a simple, rapid, and inex-
pensive screening tool that indicates the presence of readily
available NP (generally from carbonate) or stored acidity.
The outcome of the test is governed by the surficial proper-
ties of the solid material being tested, and more particularly,
the extent of soluble minerals, which may provide useful
information regarding anticipated mining-influenced water
quality. For example, acidic paste pH values in combination
Figure 7. Chondrite-normalized (Taylor and McLennan, 1985) rare earth elements (REE)
for samples from mining districts and different deposit types in New Mexico. See Table 1 for
summary of districts sampled and Figure 3 for locations
Figure 8. Ni verses Co for samples from mining districts in
New Mexico. See Table 1 for summary of districts sampled
and different deposit types, and Figure 3 for locations.
Legend is in Figure 7
Figure 9. Bi verses Te for samples from mining districts
in New Mexico. See Table 1 for summary of districts and
different deposit types sampled, and Figure 3 for locations.
Legend is in Figure 7