1
25-038
Geochemistry and Critical Mineral Potential of Stream
Sediments from the Zuni Mountains, New Mexico
Evan J. Owen
NM Bureau of Geology and Mineral Resources, New
Mexico Tech, Socorro, NM
Virginia T. McLemore
NM Bureau of Geology and Mineral Resources, New
Mexico Tech, Socorro, NM
ABSTRACT
The Zuni Mountains, located in Cibola County, New
Mexico is an uplifted area that exposes Proterozoic igneous
and metamorphic rocks overlain by Permian and younger
sediments. Sedimentary-hosted Cu deposits and fluorite
veins in the district have recorded production, but other
deposits exist. Proterozoic ultramafic rocks may host Ni and
PGE. A recent regional stream sediment survey collected
76 samples as part of an exploration geochemistry course
at New Mexico Tech with the goal of assessing the criti-
cal minerals potential of the district. Whole rock and trace
element chemistry of the sediment samples (2 mm) show
a variety of critical minerals possibly worthy of future tar-
geted exploration including up to 700 ppm As, 2100 ppm
Ba, 26 ppm Bi, 25 ppm Co, 640 ppm Cu, 145 ppm Ni,
110 ppm Sb, 170 ppm V, and 500 ppm Zr. Positive correla-
tion between Bi, As, Cu, and Sb suggest that these critical
minerals are found together within copper veins related to
shear zones in the district. Samples collected from streams
that drained outcrop of mafic and ultramafic rocks were
found to generally contain more Ni, Co, and V. Samples
elevated in Ni will be reanalyzed for PGE.
INTRODUCTION
The Zuni Mountains are located in Cibola County, New
Mexico west of the town of Grants. This west-northwest
trending range is roughly 60 miles long and 40 miles
wide. The Zuni Mountains are an uplifted area that
exposes Proterozoic igneous and metamorphic rocks over-
lain by Permian and younger sediments (Goddard, 1966
Lambert, 1983 McLemore, 1989, 2013 Strickland, 2000,
2003). Quaternary basalt flows are also found in the dis-
trict. The core of the Zuni Mountains was uplifted during
the Ancestral Rocky Mountains and Laramide orogenies
(Aldrich et al., 1986 McLemore, 2013).
The Zuni Mountains have historically been mined by
the Zuni, Acoma, and Navajo people for obsidian, basalt,
turquoise, malachite, azurite, and fluorite for ornaments
and stone tools (McLemore, 2013). Later, base and pre-
cious metals and fluorspar were mined from the district
beginning around 1900. While the total amount of metals
mined from the district was not very significant, the dis-
trict produced over 410,000 short tons of fluorspar from
1946 to 1962, with additional production before and dur-
ing World War II (McLemore, 2013). Other mineral com-
modities can be found in the Zuni Mountains including
mica, scoria, iron ore, and high-calcium limestone, with
minor to no recorded production (McLemore, 2013).
Much of the district’s mineral production came from
sedimentary-hosted copper deposits, base-metal veins
and replacements in Proterozoic rocks, and fluorite veins
(Messenger, 1979 McLemore, 2013). Episyenites and
ultramafic rocks are also found in the district, possible
sources of rare earth elements (REE) and platinum group
elements (PGE), respectively (McLemore, 2013). Nickel,
cobalt, and chromium are also found associated with ultra-
mafic rocks.
In the United States, critical minerals are defined by
the United States Geological Survey (USGS) as nonfuel
mineral commodities considered essential to the economic
and national security of the United States and have sup-
ply chains that are vulnerable to global or national disrup-
tion (Ellis, 2018). Many of these mineral commodities
are required for high technology applications, including
cell phones and computers, as well as technologies used in
the energy transition, such as electric vehicles, solar pan-
els, and wind turbines. The current (2022) USGS critical
minerals list includes 50 mineral commodities, including
fluorspar, REE, PGE, and many other mineral commodi-
ties for which the United States is nearly or 100% import
reliant. Notably, copper is absent from this list, though it is
25-038
Geochemistry and Critical Mineral Potential of Stream
Sediments from the Zuni Mountains, New Mexico
Evan J. Owen
NM Bureau of Geology and Mineral Resources, New
Mexico Tech, Socorro, NM
Virginia T. McLemore
NM Bureau of Geology and Mineral Resources, New
Mexico Tech, Socorro, NM
ABSTRACT
The Zuni Mountains, located in Cibola County, New
Mexico is an uplifted area that exposes Proterozoic igneous
and metamorphic rocks overlain by Permian and younger
sediments. Sedimentary-hosted Cu deposits and fluorite
veins in the district have recorded production, but other
deposits exist. Proterozoic ultramafic rocks may host Ni and
PGE. A recent regional stream sediment survey collected
76 samples as part of an exploration geochemistry course
at New Mexico Tech with the goal of assessing the criti-
cal minerals potential of the district. Whole rock and trace
element chemistry of the sediment samples (2 mm) show
a variety of critical minerals possibly worthy of future tar-
geted exploration including up to 700 ppm As, 2100 ppm
Ba, 26 ppm Bi, 25 ppm Co, 640 ppm Cu, 145 ppm Ni,
110 ppm Sb, 170 ppm V, and 500 ppm Zr. Positive correla-
tion between Bi, As, Cu, and Sb suggest that these critical
minerals are found together within copper veins related to
shear zones in the district. Samples collected from streams
that drained outcrop of mafic and ultramafic rocks were
found to generally contain more Ni, Co, and V. Samples
elevated in Ni will be reanalyzed for PGE.
INTRODUCTION
The Zuni Mountains are located in Cibola County, New
Mexico west of the town of Grants. This west-northwest
trending range is roughly 60 miles long and 40 miles
wide. The Zuni Mountains are an uplifted area that
exposes Proterozoic igneous and metamorphic rocks over-
lain by Permian and younger sediments (Goddard, 1966
Lambert, 1983 McLemore, 1989, 2013 Strickland, 2000,
2003). Quaternary basalt flows are also found in the dis-
trict. The core of the Zuni Mountains was uplifted during
the Ancestral Rocky Mountains and Laramide orogenies
(Aldrich et al., 1986 McLemore, 2013).
The Zuni Mountains have historically been mined by
the Zuni, Acoma, and Navajo people for obsidian, basalt,
turquoise, malachite, azurite, and fluorite for ornaments
and stone tools (McLemore, 2013). Later, base and pre-
cious metals and fluorspar were mined from the district
beginning around 1900. While the total amount of metals
mined from the district was not very significant, the dis-
trict produced over 410,000 short tons of fluorspar from
1946 to 1962, with additional production before and dur-
ing World War II (McLemore, 2013). Other mineral com-
modities can be found in the Zuni Mountains including
mica, scoria, iron ore, and high-calcium limestone, with
minor to no recorded production (McLemore, 2013).
Much of the district’s mineral production came from
sedimentary-hosted copper deposits, base-metal veins
and replacements in Proterozoic rocks, and fluorite veins
(Messenger, 1979 McLemore, 2013). Episyenites and
ultramafic rocks are also found in the district, possible
sources of rare earth elements (REE) and platinum group
elements (PGE), respectively (McLemore, 2013). Nickel,
cobalt, and chromium are also found associated with ultra-
mafic rocks.
In the United States, critical minerals are defined by
the United States Geological Survey (USGS) as nonfuel
mineral commodities considered essential to the economic
and national security of the United States and have sup-
ply chains that are vulnerable to global or national disrup-
tion (Ellis, 2018). Many of these mineral commodities
are required for high technology applications, including
cell phones and computers, as well as technologies used in
the energy transition, such as electric vehicles, solar pan-
els, and wind turbines. The current (2022) USGS critical
minerals list includes 50 mineral commodities, including
fluorspar, REE, PGE, and many other mineral commodi-
ties for which the United States is nearly or 100% import
reliant. Notably, copper is absent from this list, though it is