5
anomaly forms a north to northwest feature roughly
200 meters long. The most radioactive zone within the
anomaly reaches 1500 cps. An even more radioactive zone
was located 120 meters northeast of the main surveyed area
and reached 4000 cps. This zone appeared to be a stockpile
of mineralized sandstone from historic prospecting efforts.
Petrography and Mineralogy
Petrographic and mineralogic descriptions of these heavy
mineral sandstones will be briefly discussed here as they
are critical to the potential economics of these deposits,
however, more detailed petrography and mineral analy-
sis is planned for a future report. In general, the miner-
alogy of the heavy mineral sandstones in New Mexico is
simple, consisting primarily of variable amounts of ilmen-
ite (FeTiO3), rutile (TiO2), zircon (ZrSiO4), monazite
([Ce,La]PO4) with gangue quartz cemented by iron oxides.
The sandstones are generally fine-grained and well sorted
with subrounded to rounded clasts. Zircon crystals may still
show terminations as a result of its high hardness. Figure 6
shows a BSE photomicrograph from a previous study
(McLemore and Robison, 2016) of a characteristic heavy
mineral sandstone from the Sanostee Deposit with grains of
zircon, ilmenite, and monazite amongst subrounded quartz
cemented by iron oxides. Future mineralogical studies will
examine the rare earth element distribution between zircon
and monazite.
Whole-Rock and Trace Element Geochemical Data
Newly generated whole-rock and trace element geochemi-
cal data has been combined with existing geochemical
data from an investigation of the heavy mineral sandstone
deposit at Apache Mesa on the Jicarilla Apache Reservation
in Rio Arriba County (McLemore et al., 2016). 49 new
samples were collected over the four surveyed sites described
above. 44 geochemical samples exist from the Apache Mesa
project. More recent data was favored over historic data in
this study because of the lower detection limits for many
analytes, as well as analyses for the entire suite of REE.
Table 1 presents a summary of elements of interest from
this dataset. Notably, some analytes reach very elevated val-
ues: TiO2 (29.4%), total REE +Y (1.4%), Zr (1%), Th
(0.1%), Hf (0.16%).
Samples show distinct light REE enrichment and slight
heavy REE enrichment compared to C1 chondrite values
(Figure 7 McDonough and Sun, 1995) with prominent
Figure 5. Ground radiometric survey of the Hogback
Deposit showing a north to northwest trending radiometric
anomaly. A possible stockpile of mineralized sandstone lies
to the northeast of the main survey area
Figure 6. BSE photomicrograph of a heavy mineral
sandstone from the Sanostee Deposit. This sample shows
zircon grains (some of which are euhedral), ilmenite, and
monazite with subrounded quartz cemented by iron oxides.
From McLemore and Robison (2016)
Table 1. Summary statistics of selected elements in heavy
mineral sandstones
n=93
SiO2
(%)
Fe2O3
(%)
TiO2
(%)
Hf
(ppm)
Th
(ppm)
U
(ppm)
Zr
(ppm)
TREE+Y
(ppm)
Minimum 4.67 0.30 0.08 1.4 2.44 0.9 43 47
Maximum 96.13 69.52 29.4 1630 1000 179.5 10000 14041
Mean 58.99 19.47 5.42 176.2 128.9 20.9 3913 1473
Median 63.38 12.77 2.39 38.9 31.6 7.8 1730 502
Table 1. Summary statistics of selected elements in heavy mineral sandstones.
anomaly forms a north to northwest feature roughly
200 meters long. The most radioactive zone within the
anomaly reaches 1500 cps. An even more radioactive zone
was located 120 meters northeast of the main surveyed area
and reached 4000 cps. This zone appeared to be a stockpile
of mineralized sandstone from historic prospecting efforts.
Petrography and Mineralogy
Petrographic and mineralogic descriptions of these heavy
mineral sandstones will be briefly discussed here as they
are critical to the potential economics of these deposits,
however, more detailed petrography and mineral analy-
sis is planned for a future report. In general, the miner-
alogy of the heavy mineral sandstones in New Mexico is
simple, consisting primarily of variable amounts of ilmen-
ite (FeTiO3), rutile (TiO2), zircon (ZrSiO4), monazite
([Ce,La]PO4) with gangue quartz cemented by iron oxides.
The sandstones are generally fine-grained and well sorted
with subrounded to rounded clasts. Zircon crystals may still
show terminations as a result of its high hardness. Figure 6
shows a BSE photomicrograph from a previous study
(McLemore and Robison, 2016) of a characteristic heavy
mineral sandstone from the Sanostee Deposit with grains of
zircon, ilmenite, and monazite amongst subrounded quartz
cemented by iron oxides. Future mineralogical studies will
examine the rare earth element distribution between zircon
and monazite.
Whole-Rock and Trace Element Geochemical Data
Newly generated whole-rock and trace element geochemi-
cal data has been combined with existing geochemical
data from an investigation of the heavy mineral sandstone
deposit at Apache Mesa on the Jicarilla Apache Reservation
in Rio Arriba County (McLemore et al., 2016). 49 new
samples were collected over the four surveyed sites described
above. 44 geochemical samples exist from the Apache Mesa
project. More recent data was favored over historic data in
this study because of the lower detection limits for many
analytes, as well as analyses for the entire suite of REE.
Table 1 presents a summary of elements of interest from
this dataset. Notably, some analytes reach very elevated val-
ues: TiO2 (29.4%), total REE +Y (1.4%), Zr (1%), Th
(0.1%), Hf (0.16%).
Samples show distinct light REE enrichment and slight
heavy REE enrichment compared to C1 chondrite values
(Figure 7 McDonough and Sun, 1995) with prominent
Figure 5. Ground radiometric survey of the Hogback
Deposit showing a north to northwest trending radiometric
anomaly. A possible stockpile of mineralized sandstone lies
to the northeast of the main survey area
Figure 6. BSE photomicrograph of a heavy mineral
sandstone from the Sanostee Deposit. This sample shows
zircon grains (some of which are euhedral), ilmenite, and
monazite with subrounded quartz cemented by iron oxides.
From McLemore and Robison (2016)
Table 1. Summary statistics of selected elements in heavy
mineral sandstones
n=93
SiO2
(%)
Fe2O3
(%)
TiO2
(%)
Hf
(ppm)
Th
(ppm)
U
(ppm)
Zr
(ppm)
TREE+Y
(ppm)
Minimum 4.67 0.30 0.08 1.4 2.44 0.9 43 47
Maximum 96.13 69.52 29.4 1630 1000 179.5 10000 14041
Mean 58.99 19.47 5.42 176.2 128.9 20.9 3913 1473
Median 63.38 12.77 2.39 38.9 31.6 7.8 1730 502
Table 1. Summary statistics of selected elements in heavy mineral sandstones.