Electrical Property Measurements of the Meade Peak Phosphatic 

Shale Member of the Permian Phosporia Formation, Caribou 

County, Idaho 

By Robert J. Horton 

Any use of trade, product, or firm names is for descriptive purposes only and 

does not imply endorsement by the U.S. Government. 

Open-File Report 2004-1364 

U.S. Department of the Interior 

U.S. Geological Survey 

1
Introduction 

The U.S. Geological Survey (USGS) has studied the Permian Phosphoria 

Formation in southeastern Idaho and the Western U.S. Phosphate Field 

throughout much of the twentieth century. In response to a request by the U.S. 

Bureau of Land Management (BLM), a new series of resource and 

geoenvironmental studies was initiated by the USGS in 1998. These studies 

involved many scientific disciplines within the USGS and consist of: (1) 

integrated, multidisciplinary research directed toward resource and reserve 

estimations of phosphate in selected 7.5-minute quadrangles; (2) elemental 

residence, mineralogical and petrochemical characteristics; (3) mobilization and 

reaction pathways, transport, and disposition of potentially toxic trace elements 

associated with the occurrence, development, and use of phosphate rock; (4) 

geophysical signatures; and (5) improving the understanding of depositional 

origin. 

This report presents the preliminary laboratory results of electrical property 

measurements made on samples from the Meade Peak phosphatic shale 

member of the Permian Phosporia Formation. The samples are from a moreweathered (section A) and less-weathered (section B) section of the phosphatic 

shale member, collected from the Enoch Valley mine located in Caribou County, 

Idaho. These sections are described in detail by Tysdal and others (1999). The 

electrical measurements were made to determine if samples from different units 

can be differentiated by their geophysical signatures. 

For this laboratory study, the electrical properties were measured using 

the complex resistivity (CR) method, also known as spectral induced polarization. 

The instrumentation measures the sample’s resistivity and phase as a function of 

frequency. Resistivity and phase are complex quantities, having both real and 

imaginary components, hence the method’s name. CR measurements are made 

by transmitting electric current through the sample and measuring a received 

voltage. The current is transmitted as a sine wave and measurements are made 

over a wide band of discrete frequencies. CR data are plotted as resistivity and 

2 
phase spectra, which show the frequency dependency of the measured electrical 

properties. 

Resistivity 

Resistivity is a measure of a material’s opposition to the flow of electric 

current. Resistivity is the inverse of electric conductivity, the ability to transport 

electric charge. Resistivity units are ohm meters (ohm-m). The resistivity of rock 

and sediment are dependent on several factors including the amount of water 

present, porosity, the amount of total dissolved solids (TDS) in pore water, and 

mineral composition. The amount and TDS of pore water are typically the 

dominant factors that determine a geologic sample’s resistivity. All other factors 

being equal, dry rock is more resistive than saturated rock, and rock saturated 

with low TDS water is more resistive than rock saturated with high TDS water. 

Phase 

Phase is the angle of lag, or lead, of a sine wave with respect to a 

reference. Phase units are in milliradians (mR). Phase is a measure of charge 

storage or polarization. For these measurements the phase of the received 

voltage is measured using the current wave form as the reference. When electric 

current is transmitted through a material, a temporary induced polarization effect 

is generated. Induced polarization is a redistribution of charged particles, such 

as ions and electrons, from their equilibrium position due to the applied current. 

This redistribution or storage of charge is not an instantaneous process but 

requires a finite period to develop and to dissipate as the current varies. The 

time required to develop and dissipate the stored charge produces the phase lag 

observed between the received voltage and the transmitted current. 

Frequency Dependency 

Frequency dependency results from different mechanisms of charge 

transport and charge storage. Some of these mechanisms operate rapidly and 

are observed at relatively high frequencies, whereas slow mechanisms are 

3 
observed at lower frequencies. At low frequencies, the electrical properties of 

rocks and minerals are dominated by charge transport or conduction 

mechanisms, whereas at high frequencies charge storage or polarization 

mechanisms dominate. 

A quantitative measure of frequency dependent resistivity, historically 

used to interpret induced polarization measurements, is the percent frequency 

effect (PFE) defined as: 

PFE = 100(ρlow - ρhigh)/ ρhigh 

Where: 

ρlow = low frequency resistivity 

ρhigh = high frequency resistivity 

For this report, PFE values were calculated using data from 0.1Hz and 1.0Hz, 

which are given in table 1. 

Instrumentation 

The electrical properties presented here were measured using the nonlinear complex resistivity (NLCR) impedance spectroscopy instrumentation in the 

USGS, Crustal Imaging and Characterization Team, Petrophysics Laboratory 

located on the Denver Federal Center. This NLCR instrumentation is a 

modification of the instrumentation designed by Olhoeft (1985) and described by 

Jones (1997). The NLCR instrumentation measures electrical properties over a 

wide band of frequencies ranging from 10-3 to 106

 Hz (millihertz to megahertz) 

with three discrete frequencies being measured per decade. 

The NLCR instrumentation is limited in its ability to measure highly 

resistive material. As received, all of the Meade Peak samples were too resistive 

for the NLCR system to measure. In order to measure the samples, laboratory 

grade deionized water was added to lower their resistivity. 

Samples were measured in a cylindrical sample holder made of white 

virgin Teflon. The sample occupies a space 1 inch in diameter and three inches 

long, having a volume of 2.36 cubic inches (38.62 cm3

). Electrical signals were 

4 
transmitted to, and received from, the sample through four equally spaced 

electrodes made from bright platinum mesh. Two electrodes at the ends of the 

sample holder were used to transmit current through the sample. The voltage 

response of the sample was measured across two electrodes spaced 1 inch 

apart in the center of the sample holder. Further description of the laboratory 

procedures and apparatus used to make these measurements can be found in 

Campbell and Horton (2000). 

Sample Preparation 

Six samples were measured for this report. Each sample was measured a 

number of times with different water weight percents. The measured samples are 

splits of larger samples that have been sub-sampled for mineral (Knudsen and 

others, 2000) and chemical (Herring and others, 1999) analysis. The samples 

consisted of broken rock fragments ranging in size from fine-powder to ~2cm3

. 

Samples as received were dry, no attempt was made to preserve the original 

moisture content. Typically, samples are measured in their "as received" 

condition. However, because the Meade Peak samples were too resistive, no as 

received measurements were completed. All measurements presented here 

were made after laboratory grade, deionized water was added to each sample to 

lower its’ resistivity. 

The samples were measured at three different water contents including, 

moist, 10% water by weight, and saturated. Percent water was determined by 

weight. For the moist measurement just enough water was added to uniformly 

wet the sample, typically 4 to 5 percent by weight. The mixture was thoroughly 

stirred then loaded into the sample holder for measurement. For the saturated 

measurement the sample holder was unloaded and water was stirred into the 

sample until saturated. Typically 13 to 14 percent water by weight was required 

to saturate a sample. In the following discussions the samples will be referred to 

as “moist” or “saturated”. Water weight percent for each sample measurement is 

given in table 1. 

5
The resistivity of rock and sediment samples varies as a function of water 

content. Therefore, it may be inappropriate to compare resistivity measurements 

made on samples having different water contents. For comparison purposes, a 

third set of measurements were made on a suite of samples each having 10 

percent water by weight (table 2). For the 10 percent water samples, water was 

added to a dry split, thoroughly stirred then loaded into the sample holder for 

measurement. 

Results 

The results of the electrical property measurements are presented as 

resistivity and phase spectra given in figures 1 through 17 and summarized in 

tables one and two. The horizontal axis of each figure is logarithmic scaled 

frequency. Each figure has two traces, with resistivity plotted as square symbols 

(left legend, linear scale) and phase plotted as triangle symbols (right legend, 

logarithmic scale). Phase values are normally negative and are plotted as a solid 

triangle. However, if the phase is positive, unusual but possible, the sign of the 

value is changed and plotted as an open triangle. 

Table 1 give a summary of properties from moist and saturated 

measurements, including water weight percent, 0.002, 0.1 and 1.0Hz resistivities; 

PFE, phase peak magnitude in milliradians (mR) and phase peak position in 

frequency (Hz). Table 2 gives the electrical properties of the samples measured 

at 10 percent water content, for comparison purposes. Table 3 gives the XRD 

mineral analysis of the Meade Peak samples (from Knudsen and others, 2000). 

Discussion 

In general, the samples all have similar shaped resistivity and phase 

spectra, showing a resistivity decrease with increasing frequency; and a lowfrequency phase dispersion typically centered at ~2 Hz. The higher frequency 

6
data, typically greater than 104

, were very noisy and have been deleted from the 

spectra. 

Resistivity 

The low frequency resistivity of the Meade Peak samples varies from 28 to 

about 2550 ohm-m, depending on water weight percent. For the moist 

measurements resistivities ranged from 277.4 to 2551.85 ohm-m. For the 

saturated measurements the resistivities drop an order of magnitude, ranging 

from 28.6 to 240.6 ohm-m. 

As expected, the addition of water lowers the resistivity of samples. In 

most cases, the resistivity decreases as the water content increase. However, 

the resistivity of sample wpsb139 increased from 659 to 760 ohm-m when the 

water content was increased from 5.3 to 10 percent. The cause of this 

anomalous behavior is uncertain; however, it is probably due to sample 

heterogeneity. Because the sample was unloaded, mixed, and reloaded for each 

measurement, the actual measured material may be slightly different. If a sample 

was not sufficiently homogeneous, it is possible that different sample splits had 

different mineral compositions and or a different size fraction resulting in a 

different observed resistivity. 

There are some notable correlations between sample mineralogy and 

sample resistivity. The most conductive sample, moist or saturated, was 

wpsb157. This sample does contain the highest total amount of clay minerals 

(muscovite, illite and kaolinite), which may produce the low observed resistivity. 

The most resistive sample, moist or saturated, was wspa040. This sample 

differs from the others in that it is from the more-weathered “A” section, however, 

its bulk mineralogy is not significantly different than some samples from the lessweathered “A” section. Interestingly, sample wspa040 does have a relatively high 

total clay content, about 8 percent. Being from the more-weathered section, the 

high resistivity may be due to a loss of soluble ions, such as Ca and Na, which 

would reduce ionic conduction resulting in a relatively high resistivity. 

7
Phase 

The phase magnitude of the Meade Peak samples varies from –2.49 to 

–232mR; whereas phase peak positions range from 0.02 to 50Hz. For the moist 

measurements phase magnitude ranged from –50.55 to –141.66mR with peak 

positions ranging from 1.0 to 20Hz. For the saturated measurements phase 

magnitude ranged from –2.49 to –95.62mR with positions ranging from 0.02 to 

50Hz. Samples typically exhibit single phase peaks; however, sample wpsb059 

when saturated shows two low-magnitude peaks at relatively low frequencies. 

Phase magnitude always decreases between the moist and saturated 

measurements; however, 10 percent water weight phase values are generally 

higher than moist measurements. 

As with the resistivity data, there are some notable correlations between 

the observed phase magnitude and peak position with sample mineralogy. 

Sample wpsb157 has the highest phase peak position (20-50mR) of all the 

samples. The high peak position may be related to the samples high clay 

content. Clay minerals typically have a small grain size resulting in a high 

surface area available for surface polarization processes. Smaller grain size may 

increase the frequency of polarization responses (Bertin and Loeb, 1976; 

Sumner, 1976). 

Sample wpsb059 has the lowest overall peak magnitude (-2.49 to 

–78.34mR) and lowest peak positions (0.02 to 1.0Hz). This sample also has the 

highest carbonate fraction, about 23 percent. however, it is unclear if the low 

phase response in due to the relatively high carbonate content. Unmineralized 

carbonate rocks have been observed to have a low polarizability (Bertin and 

Loeb, 1976). 

Frequency dependency 

PFE values provide a quantitative measure of frequency dependency. 

PFE values vary considerably as a function of water weight percent. In general, 

the PFE values decrease between the moist and saturated measurements, with 

the exception of sample wpsb117. However, for two samples, wpsa040 and 

8 
wpsb139, the PFE increases at 10 percent water then decrease at higher 

saturations. The cause of this intermediate increase may be due to the 

heterogeneous nature of the samples and the fact that a different split was used 

for the 10 percent water weight measurements. 

10 Percent water weight comparison 

For the 10 percent water weight samples, wpsa040 has the highest 

resistivity, 1055 ohm-m. This is the only sample from section A, the moreweathered section, and may be more resistive due to weathering. Sample 

wpsb157 has the lowest resistivity of all samples and the highest clay content. 

The low resistivity probably results from the high clay content. 

PFE values range from 3.85 to 34.68 percent for the 10 percent water 

weight percent samples (table 2). Sample wpsb139 had the highest PFE, 

whereas sample wpsb157 had the lowest. Interestingly, sample wpsb139 does 

have the highest apatite content and the lowest total clay, whereas sample 

wpsb157 has the lowest apatite content and the highest total clay. 

The electrical properties of the 10percent water weight samples have 

some notable correlations with sample mineralogy. The sample with the highest 

phosphate (apatite) content, wpsb139, has the highest PFE, 34.68 percent, and 

largest magnitude phase peak, -232 mR. Of the samples from section B, 

wpsb139 also has the highest resistivity, more than twice that of other section B 

samples. This suggests that phosphate-rich parts of the section may be 

differentiated from non-phosphate bearing rock by their higher resistivity and 

frequency dependent electrical properties. 

The sample with the highest clay content, wpsb157, has the lowest 

resistivity, lowest PFE and the highest frequency phase peak. This suggests that 

waste units may be differentiated from phosphate bearing rock by their lower 

resistivity and frequency dependent electrical properties. 

9
Summary 

Electrical property measurements were made to characterize the electrical 

geophysical properties of samples from the Meade Peak phosphatic shale 

member of the Phosphoria Formation. The electrical properties vary primarily as 

a function of water content but also as a function of sample mineralogy. As 

received, the Meade Peak samples were too resistive to measure. The addition 

of water lowered the resistivity of samples. Moist samples are an order of 

magnitude more resistive than saturated samples. In general, the PFE values 

decrease between the moist and saturated measurements, 

The most resistive sample was from section A, the more-weathered 

section. Of the section B samples, the sample with the highest phosphate 

content also had the highest PFE, largest magnitude phase peak, and the 

highest resistivity. The sample with the lowest phosphate content has the highest 

clay content, the lowest resistivity, lowest PFE and the highest frequency phase 

peak. 

These preliminary laboratory observations suggest that frequency 

dependent electrical property measurements have some potential in 

differentiating barren from ore-bearing shale members. However, it is important 

to note that only six samples were measured for this study. Additional 

measurements, on a larger phosphatic shale sample suite, are warranted. 

10
References 

Bertin, J., and Loeb, J., 1976, Experimental and theoretical aspects of induced 

polarization, volume 1, Presentation and application of the IP method case 

histories: eds. R.G. Van Nostrand and D.S. Parasnis, Geoexploration 

Monographs, Series 1, No. 7, 250 p. 

Campbell, D., and Horton, R.J., 2000, Graphs and tables used to describe 

electrical measurements of samples of unconsolidated material, USGS 

Petrophysical Laboratory-Denver: U.S. Geological Survey Open-File Report 00-

0377, 16 p. 

Herring, J.R., Desborough, G.A., Wilson, S.A., Tysdal, R.G., Grauch, R.I., and 

Gunter, M.E., 1999, Chemical composition of weathered and unweathered strata 

of the Meade Peak Phosphatic Shale Member of the Permian Phosphoria 

Formation--A. Measured sections A and B, central part of Rasmussen Ridge, 

Caribou County, Idaho: U.S. Geological Survey Open-File Report 99-147-A, 24 

p. 

Jones, D.P., 1997, Investigation of clay-organic reactions using complex 

resistivity: Unpublished Masters thesis, Colorado School of Mines, 378 p. 

Knudsen, A.C., Gunter, M.E., and Herring, J.R., 2000, Preliminary mineralogical 

characterization of weathered and less-weathered strata of the Meade Peak 

Phosphatic Shale Member of the Permian Phosphoria Formation: Measured 

sections A and B, central part of Rasmussen Ridge, Caribou County, Idaho: U.S. 

Geological Survey Open-File Report 00-116, 74 p. 

Olhoeft, G.R., 1985, Low-frequency electrical properties: Geophysics, v. 50, no. 

12, pp. 2492-2503. 

Sumner, J.S., 1976, Principles of induced polarization for geophysical exploration: 

Elsevier, 277 p. 

Tysdal, R.G., Johnson, E.A., Herring, J.R., and Desborough, G.A., 1999, 

Stratigraphic sections and equivalent uranium (eU), Meade Peak Phosphatic 

Shale Member of the Permian Phosphoria Formation, central part of Rasmussen 

Ridge, Caribou Count y, Idaho: U.S. Geological Survey Open-File Report 99-20-

A. 

11
Table 1. Water weight percent, 0.002, 0.1 and 1.0Hz resistivity measurements, 

PFE, phase peak magnitude (in milliradians) and position (in frequency) for the 

Meade Peak samples. 

Sample Water 

% 

resistivity 

0.002Hz 

resistivity 

0.1Hz 

resistivity 

1.0Hz 

PFE Phase Peak 

mR Hz 

wpsa040.1 5.41 1272.49 1227.16 1155.27 6.22 -63 5 

wpsa040.3 14.43 190.11 186.84 180.21 3.68 -59.96 5 

wpsb047.1 5.15 2551.85 2360.42 2133.38 10.64 -102 5 

wpsb047.2 11.29 240.57 234.08 218 7.38 -80.49 5 

wpsb059.1 5.38 1272.39 1161.44 1036.24 12.08 -78.34 1 

wpsb059.4 17.02 75.26 75.51 75.02 0.65 -5.84 

-2.49 

1 

0.02 

wpsb117.1 4.84 736.76 595.87 592.59 0.55 -141.66 2 

wpsb117.3 13.86 134.29 132.27 123.69 6.94 -95.62 2 

wpsb139.1 5.29 659.78 642.32 600.85 6.90 -59.97 5 

wpsb139.4 14.15 163.23 161.9 157.59 2.73 -19.91 1 

wpsb157.1 5.04 277.4 264.25 253.31 4.32 -50.55 20 

wpsb157.3 13.82 28.58 28.38 28.17 0.75 -36.82 50 

Table 2. Comparison of resistivity measurements made at 0.002, 0.1 and 1.0Hz, 

PFE, phase peak magnitude in milliradians and phase peak position (in 

frequency) for the Meade Peak samples at 10% water weight percent. 

Sample Resistivity Resistivity Resistivity 

0.002Hz 0.1Hz 1.0Hz 

PFE Phase Peak 

mR Hz 

wpsa040.2 1055.49 960.82 829.15 15.88 -143.16 2 

wpsb059.2 346.44 321.02 298.00 7.72 -48.66 0.2 

wpsb059.3 386.61 353.89 323.59 9.36 -59.33 0.2 

wpsb117.2 255.32 268.00 254.21 5.42 -80.22 2 

wpsb139.2 760.42 668.65 498.40 34.16 -226.50 1 

wpsb139.3 748.45 661.48 491.14 34.68 -232.59 1 

wpsb157.2 62.31 63.35 61.00 3.85 -139.52 50 

12
Table 3. Mineral analysis in percent of the Meade Peak samples obtained by X-ray diffraction (from K

2000). Total clay is the sum of muscovite, illite and kaolinite. 

Sample apatite quartz muscovite illite albite orthoclase buddingtonite kaolinite dolo

wpsa040 55 25.3 6.7 0.1 0.1 2.8 9.1 1.1 wpsb047 56 22.3 4 0.1 2.3 1.6 4 0.5 8wpsb059 50 10.9 5 0.1 0.6 0.1 9.2 0.6 2wpsb117 21.7 33.7 11 0.1 8.4 1.6 10.9 0.4 6wpsb139 93 3.8 2.4 0.1 0.1 0.1 0.1 0 wpsb157 10.2 49 17 5.4 4.7 1.4 2.5 0.3 

13
wpsa040.1 @ 5.4 % water 

800 

850 

900 

950 

1000 

1050 

1100 

1150 

1200 

1250 

1300 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

Figure 1. Sample wpsa040.1 at 5.4 water weight percent. 

Figure 2. Sample wpsa040.2 at 10 water weight percent. 

wpsa040.2 @ 10.0 % water 

400 

500 

600 

700 

800 

900 

1000 

1100 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

14
Figure 3. Sample wpsa040.3 saturated at 14.4 water weight percent. 

wpsb047.1 @ 5.2 % water 

1000 

1200 

1400 

1600 

1800 

2000 

2200 

2400 

2600 

2800 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

10 

100 

1000 

Phase (negative mR) 

Figure 4. Sample wpsb047.1 at 5.2 water weight percent. 

wpsa040.3 @ 14.4% water 

140 

150 

160 

170 

180 

190 

200 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

Phase (negative mR) 

15
Figure 5. Sample wpsb047.2 saturated at 11.3 water weight percent. 

wpsb059.1 @ 5.4 % water 

600 

700 

800 

900 

1000 

1100 

1200 

1300 

1400 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

10 

100 

1000 

Phase (negative mR) 

Figure 6. Sample wpsb059.1 at 5.4 water weight percent. 

wpsb047.2 @ 11.3 % water 

100 

120 

140 

160 

180 

200 

220 

240 

260 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

16
Figure 6. Sample wpsb059.2 at 10 water weight percent. 

wpsb059.3 @ 10.0 % water 

250 

270 

290 

310 

330 

350 

370 

390 

410 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

10 

100 

1000 

Phase (negative mR) 

Figure 7. Sample wpsb059.3 at 10 water weight percent, repeat. 

wpsb059.2 @ 10.0 % water 

240 

260 

280 

300 

320 

340 

360 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

17
wpsb059.4 @ 17.0 % water 

60 

62 

64 

66 

68 

70 

72 

74 

76 

78 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

Figure 8. Sample wpsb059.4 saturated at 17.0 water weight percent. 

Figure 9a. Sample wpsb117.1 at 4.8 water weight percent. 

wpsb117.1 @ 4.8 % water 

200 

300 

400 

500 

600 

700 

800 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

10 

100 

1000

Phase (negative mR) 

18
Figure 9b. Sample wpsb117.2 at 10 water weight percent. 

wpsb117.3 @ 13.9 % water 

90 

100 

110 

120 

130 

140 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

Phase (negative mR) 

Figure 10. Sample wpsb117.3 saturated at 13.9 water weight percent. 

wpsb117.2 @ 10.0 % water 

200 

210 

220 

230 

240 

250 

260 

270 

280 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

10 

100 

1000 

Phase (negative mR) 

19
wpsb139.1 @ 5.3 % water 

350 

400 

450 

500 

550 

600 

650 

700 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

Figure 11. Sample wpsb139.1 at 5.3 water weight percent. 

Figure 12. Sample wpsb139.2 at 10 water weight percent. 

wpsb139.2 @ 10.0 % water 

0 

100 

200 

300 

400 

500 

600 

700 

800 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

10 

100 

1000

Phase (negative m

R) 

20
Figure 13. Sample wpsb139.3 at 10 water weight percent, repeat. 

wpsb139.4 @ 14.2 % water 

50 

70 

90 

110 

130 

150 

170 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

Figure 14. Sample wpsb139.4 saturated at 14.2 water weight percent. 

wpsb139.3 @ 10.0 % water 

250 

350 

450 

550 

650 

750 

850 

1.E-03 1.E-01 1.E+01 1.E+03 

Frequency (Hz) 

Resistivity (ohm-m) 

1 

10 

100 

1000 

Phase (negative mR) 

21
wpsb157.1 @ 5.0 % water 

0 

50 

100 

150 

200 

250 

300 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

10 

100 

1000 

Phase (negative mR) 

Figure 15. Sample wpsb157.1 at 5.0 water weight percent. 

Figure 16. Sample wpsb157.2 at 10 water weight percent. 

wpsb157.2 @ 10.0 % water 

25 

30 

35 

40 

45 

50 

55 

60 

65 

70 

1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 

Frequency (Hz) 

Resistivity (ohm-m) 

0.01 

0.1 

1 

10 

100 

1000

Phase (negative mR) 

22
wpsb157.3 @ 13.8 % water 

0 

5 

10 

15 

20 

25 

30 

35 

1.E-03 1.E+00 1.E+03 1.E+06 

Fre quency (Hz) 

Resistivity (ohm-m) 

0.1 

1 

10 

100 

1000 

Phase (negative mR) 

Figure 17. Sample wpsb157.3 saturated at 13.8 water weight percent. 

23