The document discusses various exploration techniques used to locate uranium deposits, including geologic mapping, remote sensing, and geophysical methods. It describes how exploration involves establishing baseline conditions, finding alteration zones and ore bodies, determining mineability and processability of ore, locating infrastructure, and refining exploration models. Key steps involve defining deposit models, selecting target areas, interpreting regional data, reconnaissance work including drilling, and discovering ore. Geologic mapping involves collecting and interpreting data in the field to understand rock distributions and make decisions about land and resource use. Remote sensing techniques like satellite imagery and hyperspectral analysis are also used to detect and identify minerals. Geophysical methods leverage variations in gravity, magnetism, conductivity and other properties to map subsurface

1. EXPLORATION
TECHNIQUES
Virginia McLemore

2. WHAT ARE THE OBJECTIVES IN
EXPLORATION?

3. WHAT ARE THE OBJECTIVES IN
EXPLORATION?
 Establish baseline/background conditions
 Find alteration zones
 Find ore body
 Determine if ore can be mined or leached
 Determine if ore can be processed
 Determine ore reserves
 Locate areas for infrastructure/operations
 Environmental assessment
 Further understand uranium deposits
 Refine exploration models

4. STEPS
 Define uranium deposit model
 Select area
 Collect and interpret regional data
 Define local target area
 Field reconnaissance
 Reconnaissance drilling
 Bracket drilling
 Ore discovery

6. Select Area
 How do we select an area to look for
uranium?

7. Select Area
 How do we select an area to look for
uranium?
• Areas of known production
• Areas of known uranium occurrences
• Favorable conditions for uranium

8. COLLECT DATA
 Historical data
 State, federal surveys
 University research programs
 Archives
 Company reports
 Web sites
 Published literature
 Prospectors

9. Methods
 Magnetic surveys
 Electromagnetic (EM,
EMI), electromagnetic
sounding
 Direct current (DC)
 GPR (Ground penetrating
radar potential)
 Seismic
 Time-domain
electromagnetic (TEM)
 Controlled source audio-
magnetotellurics (CSAMT)
 Radiometric surveys
 Induced polarization (IP)
 Spontaneous potential
(SP)
 Borehole geophysics
 Satellite imagery
 Imagery spectrometry
 ASTER (Advanced space-
borne thermal emissions
reflection radiometer)
 AVIRIS
 PIMA
 SFSI
 LIBS
 SWIR
 Multispectral

10. REMOTE SENSING

11. Remote Sensing Techniques
 Digital elevation model (DEM)
 Landsat Thematic Mapper (TM)
 ASTER (Advanced Spaceborne Thermal
Emission and Reflection Radiometer)
 Hyperspectral remote sensing (spectral
bands, 14 and >100 bands)
 NOAA-AVHRR (National Oceanic and
Atmospheric Administration - Advanced
Very High Resolution Radiometer

12. Remote sensing is the science of
remotely acquiring, processing and
interpreting spectral information about
the earth’s surface and recording
interactions between matter and
electromagnetic energy.
GROUND
Alumbrera, Ar
SATELLITE
AIRBORNE
CUPRITE, NV
Goldfield, NV
Data is collected from satellite
and airborne sensors. It is then
calibrated and verified using a
field spectrometer.
Field Spectrometer
LANDSAT
HYPERSPECTRAL

13. Sunlight Interaction with the
Atmosphere and the Earth’s Surface
The electromagnetic spectrum is a distribution of energy over specific
wavelengths. When this energy is emitted by a luminous object, it can
be detected over great distances. Through the use of instrumentation,
the technique detects this energy reflected and emitted from the
earth’s surface materials such as minerals, vegetation, soils, ice, water
and rocks, in selected wavelengths. A proportion of the energy is
reflected directly from the earth’s surface. Natural objects are
generally not perfect reflectors, and therefore the intensity of the
reflection varies as some of the energy is absorbed by the earth and
not reflected back to the sensor. These interactions of absorption and
reflection form the basis of spectroscopy and hyperspectral analysis.
Data is collected in contiguous channels by special
detector arrays. Collection is done at different
spectral and spatial resolutions depending on the
type of sensor.
Each spatial element is called a pixel. Pixel size
varies from 1/2 meters in some hyperspectral
sensors to 30 meters in Landsat and ASTER,
which are multispectral. Sensor spatial differences
and band configurations are shown below.
Source: Bob Agars
ELECTROMAGNETIC SPECTRUM

14. HYPERSPECTRAL IMAGING SPECTROSCOPY
Source:
CSIRO
Imaging spectroscopy is a technique for
obtaining a spectrum in each position of a
large array of spatial positions so that any
one spectral wavelength can be used to
make a coherent image (data cube).
Imaging spectroscopy for remote sensing
involves the acquisition of image data in
many contiguous spectral bands with an
ultimate goal of producing laboratory
quality reflectance spectra for each pixel
in an image (Goetz, 1992b). The latter
part of this goal has not yet been reached.
The major difference from Landsat is the
ability to detect individual mineral species
and differentiate vegetation species.
This "image cube" from JPL's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) shows the
volume of data returned by the instrument. AVIRIS acquired the data on August 20, 1992 when it
was flown on a NASA ER-2 plane at an altitude of 20,000 meters (65,000 feet) over Moffett Field,
California, at the southern end of the San Francisco Bay. The top of the cube is a false-color
image made to accentuate the structure in the water and evaporation ponds on the right. Also
visible on the top of the cube is the Moffett Field airport. The sides of the cube are slices
showing the edges of the top in all 224 of the AVIRIS spectral channels. The tops of the sides are
in the visible part of the spectrum (wavelength of 400 nanometers), and the bottoms are in the
infrared (2,500 nanometers). The sides are pseudo-color, ranging from black and blue (low
response) to red (high response). Of particular interest is the small region of high response in the
upper right corner of the larger side. This response is in the red part of the visible spectrum
(about 700 nanometers), and is due to the presence of 1-centimeter-long (half-inch) red brine
shrimp in the evaporation pond.

15. Exploration Techniques:
Geologic Mapping
Leann M. Giese
February 7, 2008

16.  In the mine life cycle, geologic mapping falls
under Exploration, but it effects all of the life
cycles
Mining Life Cycle (Spiral?)
Exploration
Mine
Development
Operations
Temporary
Closure
Closure
Post-Closure
Future
Land Use
Ongoing
Operations
?????
(McLemore, 2008)

17. What is geologic mapping?
 A way to gather & present geologic
data. (Peters, 1978)
 Shows how rock & soil on the earths
surface is distributed. (USGS)
 Are used to make decisions on how
to use our water, land, and
resources. (USGS)
 Help to come up with a model for an
ore body. (Peters, 1978)

18. Figure 1. Graphic representation of typical
information in a general purpose geologic
map that can be used to identify geologic
hazards, locate natural resources, and
facilitate land-use planning. (After R. L.
Bernknopf et al., 1993)
What is Geologic
Mapping? (continued)
•To better understand
the geological features
of an area
•Predict what is below
the earth’s surface
•Show other features
such as faults and
strike and dips.
(USGS (a))

19. Simplified Geologic
Map of New Mexico
(from NMBGMR).
Topographic Map of the
Valle Grande in the Jamez
Mountains

20. Geologic Mapping Equipment
 Field notebooks
 Rock hammer
 Hand Lens (10x or Hastings triplet)
 Pocket knife
 Magnet
 Clip board
 Pencils (2H-4H) and Colored Pencils
 Rapidograph-type pens and Markers
 Scale-protractor (10 and 50 or 1:1000 and 1:4000)
 Belt pouches or field vest
 30 meter tape measurer
 Brunton pocket transit
 GPS/Altimeters
 Camera
(Compton,1985)

21. Mapping types
 Aerial photographs
 Topographical bases
 Pace and Compass
 Chains
(Compton, 1985)

22. Map scales
A ratio that relates a unit of measure on a
map to some number of the same units of
measure on the earth's surface.
A map scale of 1:25,000 tells us that 1 unit
of measure represents 25,000 of the same
units on the earth's surface. One inch on
the map represents 25,000 inches on the
earth's surface.
One meter or one yard or one kilometer or
one mile on a map would represent
25,000 meters or yards or kilometers or
miles, respectively, on the earth's surface.
(from USGS (b))

23. Map scales (continued)
Map Scale One cm on
the map
represents
One km on
the Earth is
represented
on the map
by
One inch on
the map
represents
One mile on
the Earth
represented
on the map
by
1:2,000 20 meters 50
centimeters
166.67 feet 31.68
inches
1:25,000 250 meters 4
centimeters
2,083.33
feet
2.53 inches
1:100,000 1,000
meters
1
centimeter
1.58 miles 0.634
inches
1:5,000,000 50,000
meters
0.02
centimeters
78.91 miles 0.013
inches
(from USGS (b))

24. What to do first?
 Most mineral deposits are found in
districts where there has been mining
before, an earlier geologist has noticed
something of importance there, or a
prospector has filed a mineral claim
 Literature Search:
• Library (University, Government, Engineering,
or Interlibrary loans)
• State and National bureaus of mines and
geological surveys (may have drill core, well
cuttings, or rock samples available to inspect)
• Mining company information
• Maps and aerial photographs
 Is the information creditable? Is it worth
(Peters, 1978)

25. Where to go from here?
 Mapping is costly and time consuming, so an area
of interest needs to be defined
 Reconnaissance helps narrows a region to a
smaller area of specific interest
 Reconnaissace in the U.S. usually begins at
1:250,000-scale
 This large scale mapping can zone-in on areas of
interest that can then be geologically mapped in
detail (this is usually done on a 1:10,000 or
1:12,000-scale).
 Individual mineral deposits can be mapped at a
1:2,000 or 1:2,400-scale to catch its smaller
significant features.

26. Detailed Geological Mapping
 When mapping, we want to be quick,
because time is money, but not too
quick as to make a mistake or miss
something.
 Along with mapping occurs drilling,
trenching, geophysics, and
geochemistry
 Samples can be analyzed for
Uranium concentrations. This gives a
better idea of where to explore more

27. Uranium Deposit Types
 Unconformity-related deposits
• Metasedimentary rocks (mineralisation, fauletd, and brecciated) below
and Proterozoic SS. Above (pitchblende)
 Breccia complex deposits
• Hematite-rich breccia complex (iron, copper, gold, silver, & REE)
 Sandstone deposits
• Rollfront deposits, tabular deposits, tectonic/lithologic deposits
 Surficial deposits
• Young, near-surface uranium concentrations in sediments or soils
(calcite, gypsum, dolomite, ferric oxide, and halite)
 Volcanic deposits
• Acid volcanic rocks and related to faults and shear zones within the
volcanics (molybdenum & fluorine)
 Intrusive deposits
• Associated with intrusive rocks (alaskite, granite, pegmatite, and
monzonites)
 Metasomatite deposits
• In structurally-deformed rocks altered by metasomatic processes
(sodium, potassium or calcium introduction)
(Lambert et al., 1996)

28.  Metamorphic deposits
• Ore body occurs in a calcium-rich alteration zone within Proterozoic
metamoprphic rocks
 Quartz-pebble conglomerate deposits
• Uranium recovered as a by-product of gold mining
 Vein deposits
• Spatially related to granite, crosscuts metamorphic or sedimentary
rocks (coffinite, pitchblende)
 Phosphorite deposits
• Fine-grained apatie in phosphorite horizons; mud, shale, carbonates
and SS. interbedded
 Collapse breccia deposits
• Vertical tubular-like deposits filled with coarse and fine fragments
 Lignite
 Black shale deposits
 Calcrete deposits
Uranium-rich granites deeply weathered, valley-type
 Other
Uranium Deposit Types (continued)

29. Some Minerals Associated with
Uranium
 Uraninite (UO2)
 Pitchblende (U2O5.UO3 or U3O8)
 Carnotite (uranium potassium vanadate)
 Davidite-brannerite-absite type uranium titanates
 Euxenite-fergusonite-smarskite group
 Secondary Minerals:
• Gummite
• Autunite
• Saleeite
• Torbernite
• Coffinite
• Uranophane
• Sklodowskite
(Lambert et al., 1996)

30. Example of exploring a sandstone
Uranium deposit
 When looking for a sandstone-type uranium
deposit in an area that has had a radiometric
survey, our first place to focus in on the areas
where radioactivity appears to be associated with
SS. Beds. (We will disregard potassium
anomalies, below-threshold readings,
unexplained areas, and radioactive “noise”.)
 We will then map the radioactive SS. units and
other associations with our model of a SS.
uranium deposit.
 We will look for poorly sorted, medium to coarse
grained SS. beds that are associated with
mudstones or shales.
 Detailed mapping of outcrops on a smaller scale
is now appropriate. Stratigraphic sections can be
measured and projected to covered areas.
 Other radioactive areas that were disregarded
(Peters, 1978)

31. References
 Compton, R. R. (1985). Geology in the Field. United States of America and
Canada: John Wiley & Sons, Inc.
 Bernknopf, R. L., et al., 1993
Societal Value of Geologic Maps, USGS Circular 1111.
 Lambert,I., McKay, A., and Miezitis, Y. (1996) Australia's uranium
resources: trends, global comparisons and new developments, Bureau of
Resource Sciences, Canberra, with their later paper: Australia's Uranium
Resources and Production in a World Context, ANA Conference October
2001. http://www.uic.com.au/nip34.htm (accessed February 6, 2008).
 McLemore, V. T. Geology and Mining of Sediment-Hosted Uranium
Deposits: What is Uranium?. Lecture, January 30, 2008; pp. 1-26.
 New Mexico Bureau of Geology and Mineral Resources.
http://geoinfo.nmt.edu/publications/maps/home.html (accessed February
1, 2008).
 Peters, W. C. (1978). Exploration and Mining Geology. United States of
America and Canada: John Wiley & Sons, Inc.
 U.S. Geological Survey (a).
 http://ncgmp.usgs.gov/ncgmpgeomaps (accessed February 1, 2008).
 U.S. Geological Survey (b).
http://id.water.usgs.gov/reference/map_scales.html (accessed February 6,
2008).

32. GEOPHYSICAL TECHNIQUES

33. Pedram Rostami

34. Gravity Techniques
Introduction
 Lateral density changes in the
subsurface cause a change
in the force of gravity at the surface.
 The intensity of the force of gravity due
to a buried mass difference
(concentration or void) is superimposed
on the larger force of gravity due to the
total mass of the earth.
 Thus, two components of gravity forces

35. Applications
 By very precise measurement of gravity
and by careful correction for variations
in the larger component due to the
whole earth, a gravity survey can
sometimes detect natural or man-made
voids, variations in the depth to
bedrock, and geologic structures of
engineering interest.
 For engineering and environmental
applications, the scale of the problem is
generally small (targets are often from
1-10 m in size)

36.  Gravity surveys are limited by ambiguity and
the assumption of homogeneity
 A distribution of small masses at a shallow
depth can produce the same effect as a large
mass at depth.
 External control of the density contrast or the
specific geometry is required to resolve
ambiguity questions.
 This external control may be in the form of
geologic plausibility, drill-hole information, or
measured densities.
 The first question to ask when considering a
gravity survey is “For the current subsurface

37. Rock Properties
 Values for the density of
shallow materials are
determined from laboratory
tests of boring and bag
samples. Density estimates
may also be obtained from
geophysical well logging
 Table 5-1 lists the densities of
representative rocks.
 Densities of a specific rock
type on a specific site will not
have more than a few percent
variability as a rule (vuggy
limestones being one
exception). However,
unconsolidated materials such

38. Field Work
General
 Up to 50 percent of the work in a
microgravity survey is consumed in the
surveying.
 relative elevations for all stations need
to be stablished to ±1 to 2 cm. A firmly
fixed stake or mark should be used to
allow the gravity meter reader to
recover the exact elevation.
 Satellite surveying, GPS, can achieve
the required accuracy, especially the
vertical accuracy, only with the best
equipment under ideal conditions.

39. Field Work
General
 After elevation and position surveying,
actual measurement of the gravity
readings is often accomplished by one
person in areas where solo work is
allowed.
 t is necessary to improve the precision
of the station readings by repetition.
 The most commonly used survey
technique is to choose one of the
stations as a base and to reoccupy that
base periodically throughout the

40. Interpretation
 Software packages for the interpretation of
gravity data are plentiful and powerful.
 The geophysicist can then begin varying
parameters in order to bring the calculated
and observed values closer together.

41. Magnetic Methods
Introduction
 The earth possesses a magnetic field
caused primarily by sources in the core.
 The form of the field is roughly the
same, as would be caused by a dipole
or bar magnet located near the earth’s
center and aligned sub parallel to the
geographic axis.
 The intensity of the earth’s field is
customarily expressed in S.I. units as
nanoteslas (nT) or in an older unit,

42.  Many rocks and minerals are weakly
magnetic or are magnetized by
induction in the earth’s field, and cause
spatial perturbations or “anomalies” in
the earth’s main field.
 Man-made objects containing iron or
steel are often highly magnetized and
locally can cause large anomalies up to
several thousands of nT.
 Magnetic methods are generally used to
map the location and size of ferrous
objects. Determination of the
applicability of the magnetics method

43. Theory
 The earth’s magnetic field dominates most
measurementsz on the surface of the earth.
 Most materials except for permanent
magnets, exhibit an induced magnetic field
due to the behavior of the material when the
material is in a strong field such as the
earth’s.
 Induced magnetization (sometimes called
magnetic polarization) refers to the action of
the field on the material wherein the ambient
field is enhanced causing the material itself to
act as a magnet.

44. Theory(continue)
 I = k F
 k = volume magnetic susceptibility (unitless)
 I = induced magnetization per unit volume
 F = field intensity in tesla (T)
 For most materials k is much less than 1 and,
in fact, is usually of the order of 10^-6 for
most rock materials.
 The most important exception is magnetite
whose susceptibility is about 0.3. From a
geologic standpoint, magnetite and its
distribution determine the magnetic properties
of most rocks.
 There are other important magnetic minerals
in mining prospecting, but the amount and
form of magnetite within a rock determines

45.  The importance of
magnetite cannot
be exaggerated.
Some tests on rock
materials have
shown that a rock
containing 1
percent magnetite
may have a
susceptibility as
large as 10-3, or
1,000 times larger
than most rock
materials.
 Table 6-1 provides

46. Theory(continue)
 Thus it can be seen that in most
engineering and environmental scale
investigations, the sedimentary and
alluvial sections will not show sufficient
contrast such that magnetic
measurements will be of use in mapping
the geology.
 However, the presence of ferrous
materials in ordinary municipal trash
and in most industrial waste does allow
the magnetometer to be effective in
direct detection of landfills.

47. Field Work
Ground magnetic measurements are
usually made with portable
instruments at regular intervals along
more or less straight and parallel
lines which cover the survey area.
Often the interval between
measurement locations (stations)
along the lines is less than the
spacing between lines.

48.  The magnetometer is a sensitive
instrument which is used to map spatial
variations in the earth’s magnetic field.
 In the proton magnetometer, a magnetic
field which is not parallel to the earth’s
field is applied to a fluid rich in protons
causing them to partly align with this
artificial field.
 When the controlled field is removed, the
protons precess toward realignment with
the earth’s field at a frequency which
depends on the intensity of the earth’s
field. By measuring this precession
frequency, the total intensity of the field

49. The incorporation of computers and
non-volatile memory in
magnetometers has greatly increased
the ease of use and data handling
capability of magnetometers.
The instruments typically will keep
track of position, prompt for inputs,
and internally store the data for an
entire day of work.

50. To make accurate anomaly maps,
temporal changes in the earth’s field
during the period of the survey must
be considered. Normal changes
during a day, sometimes called
diurnal drift, are a few tens of nT but
changes of hundreds or thousands of
nT may occur over a few hours
during magnetic storms.
During severe magnetic storms,
which occur infrequently, magnetic
surveys should not be made. The

51. The base-station memory
magnetometer, when used, is set up
every day prior to collection of the
magnetic data.
The base station ideally is placed at
least 100 m from any large metal
objects or travelled roads and at least
500 m from any power lines when
feasible.

52. The value of the magnetic field at the
base station must be asserted
(usually a value close to its reading
on the first day) and each day’s data
corrected for the difference between
the asserted value and the base
value read at the beginning of the
day.
As the base may vary by 10-25 nT or
more from day to day, this correction
ensures that another person using

53. Interpretation.
 Total magnetic disturbances or anomalies
are highly variable in shape and
amplitude; they are almost always
asymmetrical, sometimes appear complex
even from simple sources
 One confusing issue is the fact that most
magnetometers measure the total field of
the earth: no oriented system is recorded
for the total field amplitude.
 The consequence of this fact is that only
the component of an anomalous field in
the direction of earth’s main field is

55. Additionally, the induced nature of
the measured field makes even
large bodies act as dipoles; that is,
like a large bar magnet.
 If the (usual) dipolar nature of the
anomalous field is combined with
the measurement system that
measures only the component in
the direction of the earth’s field, the
confusing nature of most magnetic

56.  To achieve a qualitative understanding
of what is occurring, consider Figure in
the next page.
 Within the contiguous United States,
the magnetic inclination, that is the
angle the main field makes with the
surface, varies from 55- 70 deg.
 The figure illustrates the field
associated with the main field, the
anomalous field induced in a narrow
body oriented parallel to that field, and
the combined field that will be

58. Uranium Exploration

59. Magnetic
Magnetic. Palaeochannel
magnetic (either positive or
negative) anomalies may be defined
if high-resolution surveys are used
and if there are sufficient magnetic
minerals in the channels or
measurable magnetic contrast
between the channel sediments and
bedrock.
Cainozoic palaeochannels are not

60. Gravity
Gravity anomalies in the earth’s
gravitational field can in some cases
be used to define the thickness and
extent of the fluvial sediments, and
hence palaeochannels, due to the
contrast in density between the
sediments and fresh bedrock. For
example, the density of sand and
clay is ~1.8g/cc and granitic
basement is 2.7 g/cc (Berkman

61. Hoover et al. (1992)

62. Hoover et al. (1992)

63. GEOCHEMICAL SAMPLING
 Ground water
 Surface water
 Stream sediments
 Soils
 Biological
 Ore samples
 Radon
 Track etch (identify radiaoactivity)

64. Surface Sampling in
Exploration
 Introduction
 Sample? Sampling?
 Sampling Programs
 Bias and Error in Sampling
 Quality Control
 Surface Sampling Methods
 Sample Handling
 Documentation Requirements
 Conclusion
 References

65. Introduction
 Sampling methods vary from simple
grab samples on existing exposures
to sophisticated drilling methods.
 As a rule, the surface of the
mineralization is obscured by various
types of overburden, or it is
weathered and leached to some
depth, thereby obscuring the nature
of the mineralization."

66. What is a sample?
What is sampling?
 A sample is a finite part of a statistical
population whose properties are studied to
gain information about the whole
(Webster, 1985).
 Sampling is the act, process, or
technique of selecting a suitable sample,
or
a representative part of a population for
the purpose of determining parameters or
characteristics of the whole population.
 Why Sample?

67. Sampling Programs
 Reconnaissance:
(1) check status of land ownership, (2) physical
characteristics of area, (3) mining history of the
area.
 Field inspection:
surface grab sampling over all exposures of
gravel, few seismic cross section, geobotanical
study, and survey for old workings.
 Sampling Plan
 Special Problems Associated with Sampling:
 Sample Processing or Washing:
 Data Processing
Data processing consists of record keeping,
reporting values, and assay procedures.

68. Sampling Plan
 Defining the population of concern
 Specifying a sampling frame, a set of
items or events possible to measure
 Specifying a sampling method for
selecting items or events from the frame
 Determining the sample size
 Implementing the sampling plan
 Sampling and data collecting
 Reviewing the sampling process

69. Sample Size
 The question of how large a sample
should be is a difficult one. Sample size
can be determined by various
constraints such as
 Cost.
 nature of the analysis to be performed
 the desired precision of the estimates
one wishes to achieve
 the kind and number of comparisons
that will be made,
 the number of variables that have to be
examined simultaneously

70. Bias and Error in Sampling
 A sample is expected to mirror the
population from which it comes, however,
there is no guarantee that any sample will
be precisely representative of the
population from which it comes.
biased:
 when the selected sample is systematically
different to the population.
The sample must be a fair representation of the population we are
interested in.
 Random errors
 The sample size may be too small to produce a
reliable estimate.
There may be variability in the population, the greater
the variability the larger the sample size needed.

71. Quality Control
 Responsibility for maintaining consistency
and ensuring collection of data of
acceptable and verifiable quality through
the implementation of a QA/QC program.
 All personnel involved in data collection
activities must have the necessary
education,
experience, and skills to perform their
duties.

72. Selecting Methods and Equipment
Soil and sediment samples may be
collected using a variety of methods and
equipment depending on the following:
 type of sample required
 site accessibility,
 nature of the material,
 depth of sampling,
 budget for the project,
 sample size/volume requirement,
 project objectives

73. Surface Sampling Methods
 Near-surface samples can be
collected with a spade, scoop, or
trowel.
 Sampling at greater depths or below
a water column may require a hand
auger, coring device, or dredge.
 As the sampling depth increases, the
use of a powered device may be
necessary to push the sampler into
the soil or sediment layers.

74. Sampling Equipments
 Tube Sampler
 Churn Drills
 Tube Corers
 Hand Driven Split-Spoon Core
Sampler
 Hand-Dug Excavations
 Backhoe Trenches; Bulldozer
Trenches
 Other Machine-Dug Excavations
 Augers
 Bucket or Clamshell Type Excavators

75. Surface Sampling
Figure 13. Wet sieving of a stream
sediment sample in the UK (Photo:
Fiona Fordyce, BGS from Salminen
and Tarvainen et al. 1998,
Floodplain sampling in southwestern
Finland (Photo: Reijo Salminen, GTK).

76. Surface Sampling
Figure 16. Humus sampling in Finland using cylindrical
sampler, and the final humus sample. (Photographs: Timo
Tarvainen, GTK).

77. Surface Sampling
The alluvial horizons at the
floodplain sediment sampling
site 29E05F3, France.
The soil sample pit at the site
41E10T3, Finland.

78. Sample Handling
 Samples should be preserved to
minimize chemical or biological changes
from the time of collection to the time of
analysis. Keep samples in air tight
containers. Sediment samples should also
be stored in such a way that the anaerobic
condition is preserved by minimizing
headspace.
 If several sub samples are collected,
soil and sediment samples should be
placed in a clean stainless steel mixing
pan or bowl and thoroughly homogenized
to obtain a representative composite

79. Sample Handling
Sample Label Information –
 Label or tag each sample container
with a unique field identification code. If
the samples are core sections, include the
sample depth in the identification.
 Write the project name or project
identification number on the label.
 Write the collection date and time on
the label.
 Attach the label or tag so that it does
not contact any portion of the sample that
will be removed or poured from the
container.
 Record the unique field identification
code on all other documentation
associated with the specific sample
container.
 Ensure all necessary information is
transmitted to the laboratory.

80. Documentation
 Thorough documentation of all field
sample collection and processing activities
is necessary for proper interpretation of
results. All sample identification, chain-of-
custody records, receipts for sample
forms, and field records should be
recorded using waterproof, non-erasable
ink in a bound waterproof notebook.
 All Procedures must be documented.

81. Sample Data
 From Sampling to Production
Pyramid
R_ MODEL
&
PRODUCTION
CHEMICAL ANALYSIS
&
GEOLOGICAL INTERPRETATION
SAMPLE PREPARATION
&
GEOLOGICAL CLASSIFICATION
SAMPLING
&
GEOLOGICAL OBSERVATION
FOUNDATION
1ST FLOOR
2ND FLOOR
3RD FLOOR

82. Conclusion
 There are many ways to sample and
many methods to calculate the value
of a deposit. It is important to
remember to use care in sampling
and to select the method that best
suits the type of occurrence that is
being sampled.

83. References
 Journal of the Mississippi Academy of
Sciences, v. 47, no. 1, p. 42.
 http://www.evergladesplan.org/pm/pm_d
ocs/qasr/qasr_ch_07.pdf
 http://www.gtk.fi/publ/foregsatlas/article.
php?id=10
 http://www.socialresearchmethods.net/tut
orial/Mugo/tutorial.htm
 http://www.policyhub.gov.uk/evaluating_
policy/magenta_book/chapter5.asp

84. Thank
you

85. Radiometric Survey
Shantanu Tiwari
Mineral Engineering
Feb 07, 2008

86. Outline
1. Introduction to Radiometric Survey
2. Radioactivity
3. Use of Radiometric Survey
4. Process
5. Case Study
6. Conclusion
7. Refrences

87. Introduction
1. Radiometrics : Measure of natural radiation in the Earth’s
surface.
2. Also Known as Gamma- Ray Spectrometry (why?).
3. Who uses it?- Geologists and Geophysicists.
4. Also useful for studying geomorphology and soils.

88. Radioactivity
1. Process in which, unstable atom becomes stable
through the process of decay of its nucleus.
2. Energy is released in the form of radiation;
(a) Alpha Particle (or helium nuclei) - Least Energy-
Travels few cm of air.
(b) Beta Particle (or electrons)- Higher Energy- Travels
upto a meter in air
(c) Gamma Rays- Highest Energy- Travels upto 300
meters in air.

89. Radioactivity (Contd.)
3. Energy of Gamma Ray is characteristic of the radioactive element it
came from.
4. Gamma Rays are stopped by water and other molecules (soil & Rock).
5. A radiometric survey measures the spatial distribution of three
radioactive elements;
(a) Potassium
(b)Thorium
(c) Uranium
6. The abundance of these elements are measured by gamma ray
detection.

90. Use of Radiometric Survey
1. Radioactive elements occur naturally in some minerals.
2. Energy of Gamma Rays is the characteristic of the element.
3. Measure the energy of Gamma Ray- Abundance.

91. Process
1. How we do radiometric survey?- By measuring the energy of Gamma
Rays.
2. Can be measure on the ground or by a low flying aircraft.
3. Gamma Rays are detected by Spectrometer.
4. Spectrometer- Counts the number of times each Gamma Ray of
particular energy intersects it.

92. Process

93. Process
5. The energy spectrum measured by a spectrometer is in MeV.
6. Range- 0 to 3 MeV.
7. The number of Gamma Ray counts across the whole spectrum is
referred as the total count (TC).

94. Process
Number
of
Gamma
Rays
(per
second)
Energy of Gamma Rays

95. Process
High
Low

96. Case Study
Gold Canyon Inc. (USA)- Bear Head Uranium Project
Bear Head Uranium Project- Red Lake Mining Camp(north-west
Ontario)
Covers a 23 km strike-length of Bear Head Fault Zone
0.05% U3O8

97. Conclusion
1. Good Technique
2. Large Area.
3. Better for plane areas.

98. References
1. http://www.goldcanyon.ca/
2. Suzanne Haydon from the Geological Survey of Victoria (Aus).

99. Thank you

100. GROUND GEOPHYSICS

101. EXPLORATION
TECHNIQUES
BY
METALLURGICAL
SAMPLING
GERTRUDE AYAKWAH
MINERAL ENGINEERING DEPARTMENT
NEW MEXICO INSTITUTE OF MINING AND TECHNOLOGY
LEROY PLACE
SOCORRO NM
February, 7th, 2008

102. Outline
 Introduction
 Purpose
 Sampling
 Sample Preparation
 Types of Metallurgical Sampling
a. Geochemical Analysis
b. Assay Techniques
 Conclusion
 References

103. Introduction
 Exploration geology is the process and science of
locating valuable mineral or petroleum which has a
commercial value. Mineral deposits of commercial
value are called ore bodies
 The goal of exploration is to prove the existence of an
ore body which can be mined at a profit
 This process occurs in stages, with early stages focusing
on gathering surface data which is easier to acquire and
later stages focusing on gathering subsurface data
which includes drilling data, detailed geophysical
survey data and metallurgical analysis

104. Purpose
The purpose of this presentation is to discuss
metallurgical sampling in exploration geology

105. Soil and Stream Sample
Preparation
 Samples are reduced and homogenized into a form
which can easily be handled by analytical personnel
 Soil and stream sediment samples are usually
sieved so that particles larger than fine sand are
removed.
 The fine particles are mixed and a portion is
removed for chemical analysis

106. Rock Sample Preparation
 Rock samples are treated in a multi-step procedure
 Rocks, cuttings, or core are first crushed to about
pea-size in a jaw crusher, then passed through a
secondary crusher to reduce the size further -
usually 1/10 inch
 This crushed sample is mixed, split in a riffle
splitter and reduced to about one-half pound or

107. Metallurgical Sampling
Types
• Geochemical Analysis
• Assay Techniques

108. Geochemical Analysis
 Involves dissolution of approximately one gram of
sample by a strong acid
 The solution which contains most of the base metals
is aspirated into a flame as in atomic absorption
spectroscopy (AAS) or into an inductively coupled
(ICP)
 AAS measures one element at a time to a normal

109. Geochemical Analysis (Cont’d)
 Whilst ICP 20 measure more elements at a time to
ppm levels
 The technique is low-cost, rapid, reasonably precise
and can be more accurate if the method is controlled
by standards.
 However accuracy is minor importance in
geochemistry as the exploration geologist seeks
patterns rather than absolute concentration
 Hence making geochemical analysis methods are
considered to be indicators of mineralization rather

110. Assay Techniques
 Wet Chemistry
 Fire Assay
 Aqua Regia Acid Digestion

111. Assay Techniques
Assay procedures uses accurate representation of
the mass of the sample being analyzed than in
geochemical analytical techniques.

112. Wet Chemistry
 “It's just an informal term referring to chemistry
done in a liquid phase. When chemists talk about
doing "wet chemistry," they mean stuff in a lab with
solvents, test tubes, beakers, and flasks” (Richard E.
Barrans Jr., Ph.D)
 It utilizes a physical measurement, either the color
of a solution, the weight or volume of a reagent, or
the conductivity of a solution after a specific
reaction
 It is a preferred technique to determine element
concentration in ore samples

113. Fire Assay
 It is used to analyzed precious metals in rock or soil
 Assay ton portion of the sample is put into a crucible
and mixed with variety of chemical (lead oxide)
 The mixture is fused at high temperature
 During fusion, beads of metallic lead are released
into the molten mixture

114. Fire Assay
 The lead particles scavenge the precious metals and
sink to the bottom of the crucible due to the
difference in density between lead and the siliceous
component of the sample known as slag.
 On completion, the molten mixture is poured into a
mold and left to solidify
 After cooling, the slag is removed from the lead
and the lead bottom is transferred into a small
crucible known as cupel and placed back into a

115. Fire Assay
 The lead is absorbed by the cupel leaving a
bead of the precious metals at the bottom of the
cupel
 Gold and silver is measured by weighing the
bead on a balance
 Silver is dissolved in nitric acid and the bead is
weighed again to determine the undissolved
gold
 Silver is calculated by the difference

116. Aqua Regia Acid Digestion
 The same procedure is used as in fire assay but
different method of measuring gold and silver
 Atomic absorption is used to measure gold and silver
 Other forms of measurement include neutron
activation analysis and flameless atomic absorption

117. Conclusion
 Geochemical analysis is considered to be
indicators of mineralization during the earlier
stages of exploration
 Assay techniques is used to determine absolute
measurement of mineralization
 It also determines if the ore deposit can be
processed by conventional milling or in situ
leaching or some other way

118. References
 http://www.alsglobal.com/Mineral/ALSContent.aspx?key=31#
metallics
 http://www.amebc.ca/primer3.htm#sampling
 http://www.newton.dep.anl.gov/askasci/chem00/chem00868.ht
m

119. DRILLING

120. Samuel Nunoo
New Mexico Bureau of Geology and
Mineral Resources
New Mexico Institute of Mining and
Technology, Socorro, NM
7TH FEBRUARY 2008
DRILLING

121. Outline
 Introduction
 Purpose
 Types

122. Introduction

123. •Drilling is the process whereby rigs or hand
operated tools are used to make holes to
intercept an ore body.
•Drilling is the ultimate stage in exploration.

124. Purpose

125. The purpose of drilling is;
•To define ore body at depth
•To access ground stability (geotechnical)
•To estimate the tonnage and grade of a
discovered mineral deposit
•To determine absence or presence of ore
bodies, veins or other type of mineral
deposit

126. Types

127. Drilling is generally categorized into 2 types:
•Percussion Drilling
This type of drilling is whereby a hammer
beats the surface of the rock, breaks it into chips.
-Reverse Circulation Drilling (RC)
•Rotary Drilling
This is the type of drilling where samples are recovered by
rotation of the drill rod without percussion of a hammer.
- Diamond Drilling
- Rotary Air Blast (RAB)
- Auger Drilling

128. Percussion Drilling
Reverse Circulation Drilling (RC)
1. This type of drilling involves the use of high pressure compressors, percussion
hammers that recover samples even after the water table.
2. The end of the hammer is a tungsten carbide bit that breaks the rock with both
percussion and rotary movement .This mostly follows a RAB intercept of an ore
body.
3. The air pressure of a RC rig can be increased by the use of a booster. This allows
for deeper drilling.
4. Samples are split by special sample splitter that is believed to pulverize the
samples. This is done to avoid metal concentrations at only section of the sample.
Contamination is checked by cleaning the splitter after every rod change either by
brush or high air pressure from rig’s air hose.
5. RC drilling is mostly followed by diamond drilling to confirm some of the RC drilling
ore intercept.
6. This type of drilling is faster and cheaper than diamond drilling

129. http://www.midnightsundrilling.com/
reverse_circulation.html

130. Rotary Drilling
Rotary Air Blast Drilling (RAB)
1. This type of drilling is common in green-field exploration and in mining pits.
2. This drilling mostly confirms soil, trench or pit anomalies.
3. It involves an air pressure drilling and ends as soon as it comes into contact with
the water table because the hydrostatic pressure is more than the air pressure.
4. Samples cannot be recovered after the water table is reached.
5. Mostly a 4meter composite sampling is conducted. Every 25th sample is
replicated to check accuracy of the laboratory analysis.
6. RAB drilling in the mine is mostly done for blast holes.

131. Rotary Drilling (Cont’d)
Diamond Drilling
1. This type of drilling uses a diamond impregnated bit that cuts the rock by rotation
with the aid of slimy chemicals in solution such as;
- DD200, expan-coarse, expan-fine, betonite and sometimes mapac A and B
for holes stability.
2. Drill sample are recovered as cores sometimes oriented for the purpose of attitude
measurement such as dip and dip directions of joints, foliation, lineation, veins.
3. Sampling involves splitting the core into 2 equal halves along the point of curvature
of foliations or along orientation lines. One half is submitted to the lab for analysis
and the other left in the core yard for future sampling if necessary.
4. Standards of known assay values are inserted in the samples to check laboratory
accuracy. Mostly high grade standards are inserted at portions of low mineralization
and low grade standards into portions of high mineralization.
5. Diamond drilling is usually the last stage of exploration or when the structural
behavior of an ore body is to be properly understood.
http://www.almadenminerals.com/geoskool/drilling.html
http://en.gtk.fi/ExplorationFinland/images/ritakallio_diamond_drilling.jpg
http://www.istockphoto.com/file_closeup/

132. Rotary Drilling (Cont’d)
Auger Drilling
1. This is a type of superficial drilling in soils and sediments. It could machine powered
auger or hand powered (manual).
2. It is mostly conducted at the very initial stage of exploration. That is after streams
sediments, soils or laterite sampling.
http://www.geology.sdsu.edu/classes/geol552/sedsampling.htm

133. Thank You !!!!

134. GEOPHYSICAL LOGGING
Frederick Ennin
Department of Environmental
Engineering

135. INTRODUCTION
 Geophysical logging is the use of physical, radiogenic or
electromagnetic instruments lowered into a borehole to gather
information about the borehole, and about the physical and
chemical properties of rock, sediment, and fluids in and near the
borehole
 Logging: “make record” of something
 First developed for the petroleum industry by Marcel and Conrad
Schlumberger in 1972.
 Schlumberger brothers first developed a resistivity tool to detect
differences in the porosity of sandstones of the oilfield at
Merkwiller-Perchelbrom, eastern France.
 Following the first electrical logging tools designed for basic
permeability and porosity analysis other logging methods were
developed to obtain accurate porosity and permeability
calculations and estimations (sonic, density and neutron logs) and
also basic geological characterization (natural radioactivity)

136. THE BOREHOLE ENVIRONMENT
Different physical properties used to
characterized the geology surrounding
a borehole-drilling
Physical properties: porosity of gravel bed,
density, sonic velocity and natural gamma
signal
Drilling can perturb the physical properties of
the rock
Factors influencing properties of rocks:
Porosity and water content
Water chemistry
Rock chemistry and minerology
Degree of rock alteration and
mineralisation
Amount of evaporites
Amount of humic acid
Temperature

137. APPLICATIONS
Became and is a key technology
in the petroleum industry.
In Mineral industry:
Exploration and monitoring
grade control in working
mines.
Ground water exploration:
delineation of aquifers and
producing zones
In regolith studies:
provides unique insights into
the composition, structure
and variability of the
subsurface
Airborne electromagnetics
used for ground truthing
airborne geophysical data
sets.

138. GEOPHYSICAL LOGGING METHODS
 MECHANICAL METHODS
caliper logging
sonic logging
 ELECTRICAL METHODS
resistivity logging
conductivity logging
spontaneous potential logging
induced polarisation
 RADIOATIVE METHODS
natural gamma rays logging
neutron porosity logging

139. MECHANICAL METHODS
Caliper logging
caliper used to measure the
diameter of a borehole and its
variability with depth.
motion in and out from the
borehole wall is recorded
electrically and transmitted to
surface recording equipment
Sonic logging
works by transmitting a sound
through the rocks of the borehole
wall
Consists of two parts:
transmitter and receivers
separated by rubber connector to
reduce the amount of direct
transmission of acoustic energy
along the tool from transmitter to
Crosshole Sonic Logging method with various kinds of defects. (Blackhawk
GeoServices, Inc.)

140. ELECTRICAL METHODS
Used in hard rock drilling
Resistivity
probes measure voltage drop by passing current through rocks
Conductivity
measurements induction probes via electromagnetic induction
either in filled or dry holes
Spontaneous potential (SP) - oldest E-method
Measures small potential differences between down
hole movable electrode and the surface earth connection
Uses wide range of electrochemical and electrokinetic processes
Induced polarisation (IP)
Commonly used in surface prospecting for minerals and downhole
applications.
Uses transmitter loop to charge the ground with high current
Transmitter loop turned off and voltage change with time is
recorded.

142. RADIOATIVE METHODS
Natural Gamma logging
simplest, high penetration distance
through rocks (1-2 m)
Depends on initial energy level and rock
density
Records levels of naturally occurring
gamma rays from rocks around
borehole
Signals from isotopes: K-40, Th-232, U-
238
and daughter products-
provides geologic information
Sophisticated tools records emission
from Bi-214 and
Tl-208 instead of U-238 and Th-232
provides detailed chemistry of rocks in
borehole
Successfully used to search for roll front
uranium deposit in regolith
Gamma-ray Borehoole Logging Probe (Lead Shielded)/System for
measurement of high-grade ore in borehole
Secondary uranium minerals associated with Gulcheru
quartzite from Gandi area, Andhra

143. RADIOATIVE METHODS
Neutron Porosity Logging
 Measures properties of the rock close to
the borehole
 Very useful tool for measuring “porosity”
 free neutrons almost unknown in the
Earth
Neutron emission source
 Active source emits into rocks around a
borehole
 Flux of neutrons recorded at the
detector is used as indicator of
conditions around surrounding rocks.
 Neutron logging provides data
under a variety of conditions in
cased and uncased boreholes. .

144. RADIOATIVE METHODS
Effects:
 Hydrogen Exception:
neutrons rapidly loose energy
due to collision with hydrogen
nuclei
(thermal neutron”-like diffusing
gas)
 Changes in Diameter of
boreholes affects results
 Calibrated with limestone
samples of differing water-filled
porosities (equivalent limestone
porosities)
 Used in conjunction with other
logging
methods in mineral geophysical

145. PROBLEMS AND LIMITATION
Problems
Biggest is the need for a “well” (ie. a borehole) to operate
High cost of drilling meaning boreholes are always
not available hence GWL will not be possible for a particular
study.
Colapse of holes in regolith systems
while wireline logs are running solved with foam drilling
or plastic casing insertion.
Limitations
Recognition that each method has weaknesses and strengths.
PVC casing- prevents electrical logging & neutron logging
(hydrogen)

146. CONCLUSIONS
 Geophysical well logging provides many different
opportunities to investigate the material making
up the wall of a borehole, be it regolith or
crystalline rock.
 A widen range of different sensors provide
information which complementary in nature. Best
results are obtained by running a suite of logs
and analyzing their similarities and differences.

147. REFERENCES
 Hallenburg, J.K., 1984. Geophysical logging for mineral and
engineering applications. PennWell Books, Tulsa, Oklahoma, 254
pp.
 Keys, W.S., 1988. Borehole geophysics applied groundwater
investigations. U.S Geol. Surv. Open File Report 87-539, Denver.
 McNeill, J.D., Hunter, J.A and Bosnar, M., 1996. Application of a
borehole induction magnetic susceptibility logger to shallow
lithological mapping. Journal of Environmental and Engineering
Geophysics 2: 77-90
 Schlumberger, 2000. Beginnings. A brief history of Schlumberger
wireline and testing, www site:
http://www.1.slb.com/recr/library/wireline/brochure/beginnings.ht
ml
 Sheriff, R.E., 1991. Encyclopedic Dictionary of Exploration
Geophysics, Society of Exploration Geophysicists, Tulsa,
Oklahoma, 376 pp.
 Keys, Scott, MacCary, L. M., 1971 Application of Borehole
Geophysics to Water-Resources Investigations, Techniques of
Water-Resources Investigations Book 2, Chapter E1,
http://pubs.er.usgs.gov/usgspubs/twri/twri02E1
 Keys, W. S., 1990, Techniques of Water-Resources Investigations,
Book 2, Chapter E-2, U. S. Geological Survey,
http://pubs.er.usgs.gov/usgspubs/twri/twri02E2

148. REFERENCES
 Stevens, H. H. Jr., Ficke, J. F., and Smoot, G. F., 1976, Techniques of Water-
Resources Investigations Book 1, Chapter D1, Water Temperature—Influential
Factors, Field Measurement, and Data Presentation, U.S. Geological Survey,
http://pubs.er.usgs.gov/usgspubs/twri/twri01D1
 http://images.google.com/imgres?imgurl=http://id.water.usgs.gov/projects/INL/ima
ges/therm_1.gif&imgrefurl=http://id.water.usgs.gov/projects/INL/geophys.html&h=4
72&w=474&sz=11&hl=en&start=13&um=1&tbnid=U3z2Z4OhRFxj5M:&tbnh=128&tb
nw=129&prev=/images%3Fq%3DPICTURES%2BOF%2BGEOPHYSICAL%2BLOGGING
%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:*:IE-
SearchBox%26rlz%3D1I7GGIC
 http://images.google.com/imgres?imgurl=http://www.nga.com/graphics/Geo_ser_B
orehole_logging(sketch).gif&imgrefurl=http://www.nga.com/Geo_ser_Borehole_loggi
ng_tech.htm&h=292&w=350&sz=11&hl=en&start=1&um=1&tbnid=yn-
xod1ZgFgn3M:&tbnh=100&tbnw=120&prev=/images%3Fq%3DPICTURES%2BOF%2
BGEOPHYSICAL%2BLOGGING%26um%3D1%26hl%3Den%26rls%3Dcom.microsoft:
*:IE-SearchBox%26rlz%3D1I7GGIC

149. METALURGICAL SAMPLING

150. Methods
 Magnetic surveys
 Electromagnetic (EM,
EMI), electromagnetic
sounding
 Direct current (DC)
 GPR (Ground penetrating
radar potential)
 Seismic
 Time-domain
electromagnetic (TEM)
 Controlled source audio-
magnetotellurics (CSAMT)
 Radiometric surveys
 Induced polarization (IP)
 Spontaneous potential
(SP)
 Borehole geophysics
 Satellite imagery
 Imagery spectrometry
 ASTER (Advanced space-
borne thermal emissions
reflection radiometer)
 AVIRIS
 PIMA
 SFSI
 LIBS
 SWIR
 Multispectral

151. OTHER TECHNIQUES
 Fluid inclusion analyses
 Stable and radiometric isotopes
 Computer modeling

152. STEPS
 Define uranium deposit model
 Select area
 Collect and interpret regional data
 Define local target area
 Field reconnaissance
 Reconnaissance drilling
 Bracket drilling
 Ore discovery