3
select, profile samples, and drill core samples as described
below. Samples are archived at NMBGMR for future
examination. Two separate splits of each samples are gener-
ally collected: one split for chemical analyses that is submit-
ted to the chemical laboratory and a second split that is
archived at NMBGMR. Selected sample sites are located
using handheld GPS and a digital photograph is taken
at all localities. Photographs provide visual record of the
sample site the photograph form identifies site specifics,
provides basic location and other data about the photo-
graph. Location information by global positioning system
(GPS), type of sample, and field and laboratory petro-
graphic descriptions are collected. Geologic observations
are recorded on the field description form or field book.
Hand specimen description provides a record of what was
collected, aids in petrographic description, and provides
information on sample for the labs (high S may be treated
differently than low S). The hand specimen description is
the preliminary data required to determine what samples
need specific detailed analyses. Location, type of sample,
and other descriptive data are entered into the project
database.
Composite samples include sampling along the width
and thickness of the sedimentary layer or bed in order to
obtain a representative sample of the unit. Multiple sub-
samples are collected and homogenized for a composite
sample.
Select samples include hand specimens of mineralized
rocks (including ore samples), grab samples of the mine
wastes, samples from individual cells, etc. from anywhere
in the mine or outcrop being sampled and are collected for
specific purposes (to identify minerals, separate chemical
analyses, etc.). These samples are collected separate from
the composite sample. The volume or number of samples
collected is highly dependent on the type of laboratory
test to be conducted and the availability of the sample.
Weathering surfaces were removed from rock samples. If
the purpose of sampling is for geochemical analysis, the
samples were broken into smaller chips. Samples were
stored in a well-labeled bag.
Profile samples are generally composite samples col-
lected from individual stratigraphic layers or beds along a
vertical exposed section of an outcrop, road cut, or open pit
wall, if safe. The surface of the profile was cleaned gently
using a pick to prevent the edges from caving in. Identify
the changes in different lithologies (i.e., color, thickness,
Figure 2. Location map of coal fields in the San Juan basin,
New Mexico (modified from Hoffman, 2017). Active coal
mines are surface operations. Lee Ranch mine suspended
operations in 2016, but reopen in 2024. Coal fields are
summarized in Table 1 (end of report). Only the Four
Corners power plant remains open in New Mexico
Figure 3. Stratigraphy of the San Juan Basin, New Mexico.
Note the stratigraphic units that have gas, petroleum, coal,
and uranium potential. Many of these same stratigraphic
units have the potential for critical minerals and REE (from
Brister and Hoffman, 2002)
select, profile samples, and drill core samples as described
below. Samples are archived at NMBGMR for future
examination. Two separate splits of each samples are gener-
ally collected: one split for chemical analyses that is submit-
ted to the chemical laboratory and a second split that is
archived at NMBGMR. Selected sample sites are located
using handheld GPS and a digital photograph is taken
at all localities. Photographs provide visual record of the
sample site the photograph form identifies site specifics,
provides basic location and other data about the photo-
graph. Location information by global positioning system
(GPS), type of sample, and field and laboratory petro-
graphic descriptions are collected. Geologic observations
are recorded on the field description form or field book.
Hand specimen description provides a record of what was
collected, aids in petrographic description, and provides
information on sample for the labs (high S may be treated
differently than low S). The hand specimen description is
the preliminary data required to determine what samples
need specific detailed analyses. Location, type of sample,
and other descriptive data are entered into the project
database.
Composite samples include sampling along the width
and thickness of the sedimentary layer or bed in order to
obtain a representative sample of the unit. Multiple sub-
samples are collected and homogenized for a composite
sample.
Select samples include hand specimens of mineralized
rocks (including ore samples), grab samples of the mine
wastes, samples from individual cells, etc. from anywhere
in the mine or outcrop being sampled and are collected for
specific purposes (to identify minerals, separate chemical
analyses, etc.). These samples are collected separate from
the composite sample. The volume or number of samples
collected is highly dependent on the type of laboratory
test to be conducted and the availability of the sample.
Weathering surfaces were removed from rock samples. If
the purpose of sampling is for geochemical analysis, the
samples were broken into smaller chips. Samples were
stored in a well-labeled bag.
Profile samples are generally composite samples col-
lected from individual stratigraphic layers or beds along a
vertical exposed section of an outcrop, road cut, or open pit
wall, if safe. The surface of the profile was cleaned gently
using a pick to prevent the edges from caving in. Identify
the changes in different lithologies (i.e., color, thickness,
Figure 2. Location map of coal fields in the San Juan basin,
New Mexico (modified from Hoffman, 2017). Active coal
mines are surface operations. Lee Ranch mine suspended
operations in 2016, but reopen in 2024. Coal fields are
summarized in Table 1 (end of report). Only the Four
Corners power plant remains open in New Mexico
Figure 3. Stratigraphy of the San Juan Basin, New Mexico.
Note the stratigraphic units that have gas, petroleum, coal,
and uranium potential. Many of these same stratigraphic
units have the potential for critical minerals and REE (from
Brister and Hoffman, 2002)