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 Spontaneous potential (SP)
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. SATELLITE AIRBORNE GROUND
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.
LANDSAT
AIRBORNE
HYPERSPECTRAL
GROUND
Field Spectrometer
Alumbrera, Ar
Data is collected from satellite and airborne sensors. It is then calibrated and verified using a field spectrometer.
CUPRITE, NV
Goldfield, NV

13. Sunlight Interaction with the Atmosphere and the Earth’s Surface
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.
ELECTROMAGNETIC SPECTRUM
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.
Source: Bob Agars

14. HYPERSPECTRAL IMAGING SPECTROSCOPY
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.
Source: CSIRO
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. Mining Life Cycle (Spiral?)
In the mine life cycle, geologic mapping falls under Exploration, but it effects all of the life cycles
Closure
Ongoing Operations
Post-Closure
Temporary Closure
Exploration
Future Land Use
Mine Development
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. 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))
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)

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

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)
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
feet
31.68 inches
1:25,000
250 meters
4 centimeters
2, 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 exploring?
(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.
(Peters, 1978)

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 or drill in an area.

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. Uranium Deposit Types (continued)
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

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 may be given a second look for other possibilities for further investigations.
(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 (accessed February 6, 2008).
McLemore, V. T. Geology and Mining of Sediment-Hosted Uranium Deposits: What is Uranium?. Lecture, January 30, 2008; pp
New Mexico Bureau of Geology and Mineral Resources. (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).
(accessed February 1, 2008).
U.S. Geological Survey (b). (accessed February 6, 2008).

32. GEOPHYSICAL TECHNIQUES

33. Gravity and magnetic exploration
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 are measured at the earth’s surface: first, a general and relatively uniform component due to the total earth, and second, a component of much smaller size which varies due to lateral density changes (the gravity anomaly).

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)
Station spacings are typically in the range of 1-10 m
Even a new name, microgravity, was invented to describe the work.

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 model, can the resultant gravity anomaly be detected?”.
Inputs required are the probable geometry of the anomalous region, its depth of burial, and its density contrast.
A generalized rule of thumb is that a body must be almost as big as it is deep. 36

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 as alluvium and stream channel materials may have significant variation in density.

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.
High station densities are often required. It is not unusual for intervals of 1-3 m to be required to map anomalous masses whose maximum dimension is 10 m.

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 working day.
The observed base station gravity readings are then plotted versus time, and a line is fitted to them to provide time rates of drift for the correction of the remainder of the observations.

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.
Parameters usually available for variation are the vertices of the polygon, the length of the body perpendicular to the traverse, and the density contrast. Most programs also allow multiple bodies.

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, gamma (g): 1 g = 1 nT = 10-3 μT. Except for local perturbations, the intensity of the earth’s field varies between about 25 and 80 μT over the coterminous United States

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 should be done by an experienced engineering geophysicist.
Modeling and incorporation of auxiliary information may be necessary to produce an adequate work plan.

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.
The field caused by such a material is directly proportional to the intensity of the ambient field and to the ability of the material to enhance the local field, a property called magnetic susceptibility. The induced magnetization is equal to the product of the volume magnetic susceptibility and the inducing field of the earth:

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 how most rocks respond to an inducing field.
Iron, steel, and other ferromagnetic alloys have susceptibilities one to several orders of magnitude larger than magnetite. The exception is stainless steel, which has a small susceptibility.

45. The importance of magnetite cannot be exaggerated
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 some typical values for rock materials.
Note that the range of values given for each sample generally depends on the amount of magnetite in the rock

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.
Other ferrous objects which may be detected include pipelines, underground storage tanks, and some ordnance.

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 can be determined.
The physical basis for several other magnetometers, such as the cesium or rubidium-vapor magnetometers, is similarly founded in a fundamental physical constant. The optically pumped magnetometers have increased sensitivity and shorter cycle times (as small as 0.04 s) making them particularly useful in airborne applications.

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.
Downloading the information to a personal computer is straightforward and plots of the day’s work can be prepared each night.

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 correction for diurnal drift can be made by repeat measurements of a base station at frequent intervals.
The measurements at field stations are then corrected for temporal variations by assuming a linear change of the field between repeat base station readings.

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.
The base station location must be very well described in the field book as others may have to locate it based on the written description.

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 nT or more from day to day, this correction ensures that another person using the SAME base station and the SAME asserted value will get the same readings at a field point to within the accuracy of the instrument.

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 measured.
Figure 6-1 illustrates this consequence of the measurement system
Anomalous fields that are nearly perpendicular to the earth’s field are undetectable

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 interpretations can be appreciated

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 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 measured by the total-field magnetometer.
The scalar values which would be measured on the surface above the body are listed.
From this figure, one can see how the total-field magnetometer records only the components of the anomalous field.

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 usually visible on regional magnetic data, as they are relatively shallow features, but careful use of detailed surveys may assist in locating channel deposits.

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 1995).

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."
If existing exposures are available, they can be tested for potentially valuable minerals by taking a grab sample and panning the sample. The disadvantages are that you can only sample what is on the surface and no quantitative information can be produced.

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.
These are (1) large rocks and boulders, (2) erratic high values, (3) uncased holes, (4) small diameter holes, and (5) salting.

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

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 sample.

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 3RD FLOOR 2ND FLOOR
1ST FLOOR
Sampling and geological observation- field
Sampling preparation and class.-lab and core yard
Chemical analysis (lab) and geological (interpretation Light table)
Resource model and geostatistics- Office
FOUNDATION

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.

84. Thank you

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

86. Outline Introduction to Radiometric Survey Radioactivity
Use of Radiometric Survey
Process
Case Study
Conclusion
Refrences

87. Introduction
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 Energy is released in the form of radiation;
1. Process in which, unstable atom becomes stable through the process of decay of its nucleus.
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.)
Energy of Gamma Ray is characteristic of the radioactive element it came from.
Gamma Rays are stopped by water and other molecules (soil & Rock).
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
Radioactive elements occur naturally in some minerals.
Energy of Gamma Rays is the characteristic of the element.
Measure the energy of Gamma Ray- Abundance.

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

92. Process

93. Process The energy spectrum measured by a spectrometer is in MeV.
Range- 0 to 3 MeV.
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. Gold Canyon Inc. (USA)- Bear Head Uranium Project
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
Good Technique
Large Area.
Better for plane areas.

98. References http://www.goldcanyon.ca/
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
Geochemical Analysis
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 250 grams. This 250 grams is placed in a pulverizer where it is reduced further to -150 mesh for analysis

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 sensitivity of about 1 ppm

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 than absolute measurement of mineralization.

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 furnace

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

119. DRILLING

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

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)
This type of drilling involves the use of high pressure compressors, percussion hammers that recover samples even after the water table.
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.
The air pressure of a RC rig can be increased by the use of a booster. This allows for deeper drilling.
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.
RC drilling is mostly followed by diamond drilling to confirm some of the RC drilling ore intercept.
This type of drilling is faster and cheaper than diamond drilling

129.
reverse_circulation.html

130. Rotary Drilling Rotary Air Blast Drilling (RAB)
This type of drilling is common in green-field exploration and in mining pits.
This drilling mostly confirms soil, trench or pit anomalies.
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.
Samples cannot be recovered after the water table is reached.
Mostly a 4meter composite sampling is conducted. Every 25th sample is replicated to check accuracy of the laboratory analysis.
RAB drilling in the mine is mostly done for blast holes.

131. Rotary Drilling (Cont’d)
Diamond Drilling
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.
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.
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.
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.
Diamond drilling is usually the last stage of exploration or when the structural behavior of an ore body is to be properly understood.

132. Rotary Drilling (Cont’d)
Auger Drilling
This is a type of superficial drilling in soils and sediments. It could machine powered auger or hand powered (manual).
It is mostly conducted at the very initial stage of exploration. That is after streams sediments, soils or laterite sampling.

133. Thank You !!!!

134. Frederick Ennin Department of Environmental Engineering
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 receiver
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
Secondary uranium minerals associated with Gulcheru quartzite from Gandi area, Andhra
Gamma-ray Borehoole Logging Probe (Lead Shielded)/System for measurement of high-grade ore in borehole

143. RADIOATIVE METHODS Neutron Porosity Logging Neutron emission source
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 logging in hard rock (lower porosities)

145. PROBLEMS AND LIMITATION
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., Geophysical logging for mineral and engineering applications. PennWell Books, Tulsa, Oklahoma, 254 pp.
Keys, W.S., Borehole geophysics applied groundwater investigations. U.S Geol. Surv. Open File Report , Denver.
McNeill, J.D., Hunter, J.A and Bosnar, M., Application of a borehole induction magnetic susceptibility logger to shallow lithological mapping. Journal of Environmental and Engineering Geophysics 2: 77-90
Schlumberger, Beginnings. A brief history of Schlumberger wireline and testing, www site:
Sheriff, R.E., 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,
Keys, W. S., 1990, Techniques of Water-Resources Investigations, Book 2, Chapter E-2, U. S. Geological Survey,

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,

149. METALURGICAL SAMPLING

150. Methods Magnetic surveys Spontaneous potential (SP)
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