GEOLOGICAL SURVEY CIRCULAR 738

Analytical precision of 

One-Sixth Order Semiquantitative 

Spectrographic analysis
Analytical precision of 

One-Sixth Order Semiquantitative 

Spectrographic analysis

By J. M. Motooka and D. J. Grimes 

GEOLOGICAL SURVEY CIRCULAR 738

Superimposed frequency diagrams represent the 

precision for low, medium, and high concentrations 

of the thirty elements routinely determined by the 

Denver-based mobile spectrographic laboratories

1976
United States Department of the Interior

THOMAS S. KLEPPE, Secretory

Geological Survey

V. E. McKelvey, Director

Library of Congress Cataloging in Publication Data

Motooka, J. M.

Analytical precision of one-sixth order semiquantitative spectrographic analysis.

(Geological Survey Circular 738}

Bibliography: p.

1. Ores Sampling and estimation. 2. Spectrum enalysis.

I. Grimes, David J., 1943- joint author. II. Title. III. Series: United States Geological Survey

Circular 738. 

QE75.C5 no. 738 [TN555] 557.3'08s [552'.06] 76-608209

Free on application to the Branch of Distribution, Eastern Region, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304
CONTENTS

Page Page

Abstract..................................................................................... 1 Explanation of graphs and tables Continued

Introduction.........................................................,....................! Graphs................................................................................3

Spectrographic standards.......................................................2 Tables..................................................................................3

Experimental design................................................................ 2 Discussion.................................................................................3

Explanation of graphs and tables ........................................3 References cited........................................................................4

ILLUSTRATIONS

FIGURES 1-30 Frequency diagrams and tabular summaries of elements: Page

1. Iron............................................................................................................ 5

2. Magnesium............................................................................................... 5

3. Calcium..................................................................................................... 6

4. Titanium................................................................................................... 6

5. Manganese............................................................................................... 7

6. Silver......................................................................................................... 7

7. Arsenic...................................................................................................... 8

8. Gold........................................................................................................... 9

9. Boron......................................................................................................... 10

10. Barium...................................................................................................... 11

11. Beryllium................................................................................................./12

12. Bismuth.....................................................................................................;l3

13. Cadmium..................................................................................................'13

14. Cobalt........................................................................................................l4

15. Chromium................................................................................................. 15

16. Copper.......................................................................................................'^

17. Lanthanum............................................................................................... 16

18. Molybdenum............................................................................................. 17

19. Niobium.................................................................................................... 17

20. Nickel........................................................................................................ 18

21. Lead........................................................................................................... 19

22. Antimony.................................................................................................. 19

23. Scandium.................................................................................................. 20

24. Tin.............................................................................................................. 21

25. Strontium.................................................................................................. 22

26. Vanadium................................................................................................. 23

27. Tungsten................................................................................................... 23

28. Yttrium...................................................................................................... 24

29. Zinc............................................................................................................ 24

30. Zirconium.................................................................................................. 25

in
Analytical Precision of One-Sixth Order 

Semiquantitative Spectrographic Analysis

By J. M. Motooka and D. J. Grimes

ABSTRACT

Over 2,700 separate analyses were made on 22 different 

geologic samples selected to cover wide concentration 

ranges for the 30 elements studied. The precision for low, 

medium, and high concentrations of each element determined is represented by superimposed frequency diagrams 

and displays the frequency of reported values occurring 

within one-sixth order reporting intervals about the mean. 

Results are drived from mixed analyst and instrument 

conditions with no controls enforced other than randomization of samples. The precision of the six-step (one-sixth 

order) semiquantitative spectrographic analysis utilized by 

the Denver-based mobile laboratories exceeds that which is 

necessary for exploration geochemistry. Disallowing results 

obtained near the detection levels, the repeatability of the 

method, in general, is shown to be within on adjoining 

reporting interval on each side of the mean, 83 percent of the 

time, and within two adjoining reporting intervals on each 

side of the mean 96 percent of the time.

INTRODUCTION

Spectrochemical analysis is one of the most 

widely used analytical systems in geochemical 

exploration. In the six-step semiquantitative 

spectrographic method commonly used in the 

U.S. Geological Survey and first described by 

Myers, Havens, andDunton (1961), and later by 

Ward, Lakin, Canney, and others (1963), and 

Grimes and Marranzino (1968), the light emitted 

at specific wavelengths by excited atoms of an 

unknown sample is photographed and results 

are obtained by visually comparing line densities of the unknown sample to the densities of 

known standard concentrations. The principal 

advantages, not found simultaneously in other 

types of analysis, are: a rapid multi-element 

analysis, adequate detection levels, relatively 

inexpensive cost per determination, and utilization of small sample sizes (10 milligrams or 

less). The mobile laboratories (Canney and 

others, 1957) also provide geologic field crews a

means of "on-site" analytical support which 

results in a more efficient planning of sampling 

programs by day-to-day evaluation of analytical data.

The basis of this report is a graphic illustration of the precision of each element at three 

concentration levels (low, medium, and high) 

evaluated according to occurrence within onesixth order intervals about the respective mean 

values. The results of this investigation indicate 

a level of precision in excess of that required for 

geological exploration needs. In general, the 

repeatability within one (one-sixth order) reporting interval of the mean is approximately 83 

percent and approximately 96 percent within 

two (one-sixth order) reporting intervals of the 

mean.

The primary reason for initiating this study 

was to provide information on the precision of 

the six-step semiquantitative spectrographic 

method, thereby determining the degree of 

confidence that can be placed on the reported 

values of the 30 elements chosen for analysis. In 

order to provide the necessary information to set 

a confidence level, the authors felt it important 

to design the study to investigate the sources of 

variation that affect precision. The study was 

also designed to simulate the variations of 

normal routine conditions.

The data were collected over a 3-year period 

and were generated by 7 analysts using 6 

spectrographic instruments located in both field 

oriented laboratories and "in-house" laboratories. Because of the design of the study, it should 

be noted that the precision results shown here 

are representative of the spectrographic laboratory as a whole. Any one individual, under 

controlled conditions, would be expected to 

produce better results.
This report summarizes the efforts of numerous U.S. Geological Survey personnel. Special 

mention is given of the contributions made by A. 

T. Miesch for his initial consultation in setting 

up the study; by R. J. Smith and L. O. Wilch for 

handling the computer aspects; and by K. J. 

Curry, G. W. Day, J. A. Domenico, C. L. Forn, R. 

T. Hopkins, Jr., and D. F. Siems for performing 

the analytical work.

SPECTROGRAPHIC 

STANDARDS

In the six-step method used by the Denverbased mobile laboratories, synthetic standards 

are prepared from spectrographically pure 

compounds (usually oxides and some carbonates) and are diluted in one-third-order intervals, thereby providing three steps per order of 

magnitude. In order to obtain six steps per order 

of magnitude, the intermediate steps are visually interpolated.

Appropriate quantities of the sought-after 

elements are added and thoroughly mixed with 

an average rock matrix consisting of major 

elements (31 percent Si, 5 percent Al, 7 percent 

Fe, 2 percent Ca, 0.6 percent Mg, 1.6 percent Na, 

1.1 percent K). Standards containing 

successively lower amounts of the elements are 

made by use of a dilution factor equal to the 

reciprocal of the cube root 10 (0.464). Analytical 

results are reported as six steps per order of 

magnitude (10, 7, 5, 3, 2, 1.5, or powers of 10 of 

these numbers) which are approximate 

geometric midpoints of concentration ranges 

whose boundaries are as follows:

Reported value Interval

10 ............................ 8.3- 12

7 ............................ 5.6-S.3

5 ............................ 3.8-5.6

3 .................... M ...... 2.6-3.8

2 ............................ 1.8-2.6

1.5 ........................... 1.2-1.8

Details on the technique of preparing spectrographic standards are further described by 

Grimes and Marranzino (1968).

EXPERIMENTAL DESIGN

The study was designed to simulate normal 

routine conditions for analyses of the test 

samples. The routine procedure for the Denverbased mobile spectrographic laboratories is to 

analyze all silicate samples by the same 

analytical method and to employ the same set of 

spectrographic standards for obtaining results that is, no distinction for modification 

of procedure is used for different types of rocks, 

soils, or stream sediments. Thirty elements, 

each of whose concentrations may range 

widely, are routinely determined in the six-step 

spectrographic method. As detection levels are 

approached, precision of the analysis is greatly 

diminished. To provide the various concentration levels of all elements reported, 15 geologic 

samples were originally selected, and 7 "geochemical exploration reference samples" were 

added later to fill some of the missing concentration levels (Allcott and Lakin, 1974). The 

samples were selected according to the concentration of a certain element or elements without 

regard to geologic material types. Therefore, 

several types of sample media were included, 

such as stream sediments, soils, drill cores, and 

various rock types. The detectable gold in two 

samples is in the micrometre to sub- MHI particle 

size. They were specifically selected because of 

their homogeneity and should not be considered 

as characteristic of all gold-bearing geologic 

materials. Gold samples of larger particle size 

would not be expected to produce such precise 

results when using 10-milligram sample sizes.

The original 15 samples were not given any 

special preparation prior to analysis, whereas 

the "geological reference samples" were prepared under well-defined conditions, specifically to insure homogeneity (Allcott and Lakin, 

1975).

The 22 study samples were split into 600 subsamples. Random numbers were assigned and 

the 600 subsamples were divided into groups of 

40 samples each for distribution and rotation 

among the analysts. A coded number was 

assigned to each split, to distinguish sample, 

spectrographer, spectrographic instrument, "inhouse" or field laboratory, and the year in which 

the work was performed. The purpose of this 

report is not to provide individual breakdowns 

but to determine the precision of the entire 

laboratory under the combined influence of 

precision-affecting variables.

The study samples were analyzed along with 

routine samples at the rate of approximately 

1 split to every 20 routine samples. At periodic 

intervals the groups of 40 splits were rotated
among the spectrographers so that all the 

original 22 test samples were analyzed numerous times (approximately 20) by all 7 spectrographers utilizing different spectrographic 

instruments both "in-house" and in field laboratories. Over a 3-year period, each study sample 

was analyzed a minimum of 83 times, and some 

as many as 154 times, resulting in over 2,700 

separate analyses. The data were stored in a 

computer-storage system for easy retrieval.

EXPLANATION OF GRAPHS 

AND TABLES

GRAPHS

The line graphs (figs. 1-30) are frequency 

diagrams of histograms obtained from a computer program designed to generate graphical 

displays. Each figure is representative of a 

single element, and most contain three superimposed graphs representative of the precision of 

the element at a low, medium, and high 

concentration level. Where two or more of the 

same concentration levels were present, among 

the 22 test samples, selection was made on an 

arbitrary basis. The concentration level of each 

graph is indicated. Elements having only two 

line graphs are Au, Cd, Nb, Sc, and W, where 

only two distinct concentration levels could be 

found in the 22 test samples. Note that each line 

graph is representative of a concentration level 

of an element in only 1 of 22 test samples and is 

identified by sample number in the tables so 

that comparisons of different elements within a 

sample can be made.

The frequency diagrams for the same element 

are superimposed to display the variable 

skewness at different concentration ranges. 

Since each line graph is a different concentration range, in order to superimpose them the 

mean value is set at zero (abscissa axes). 

Variations in the analysis from the mean 

(reported as geometric midpoints of the spectrographic reporting intervals) are then 

designated +1, -1, +2, -2, and so forth, with 

respect to the mean value at zero, and plotted 

according to frequency. The interval frequencies are rounded to whole numbers, and the 

sums of the plot-points on the diagrams are 

within 1 percent of 100.

In the six-step semiquantitative spectrographic method, if a spectrographic line is

detected but is less than the lowest discernible 

standard line, the value is designated as L (less 

than amount shown); if no line is detected, the 

value is designated as N (not detected); and if 

the line is greater than the highest standard, the 

value is designated as G (greater than). These 

values (L, N, and G) are termed "qualified 

values." Inasmuch as only unqualified values 

can be used for calculations, in this report, all 

L's were assigned the next lowest reporting 

value, and all remaining qualified values (N and 

G) were dropped from the calculation of the 

mean values. Where N's and G's occur, the 

histograms end abruptly with the symbol S in 

their respective spectrographic interval.

TABLES

The tables are capsule summaries of the 

frequency diagrams. Each test sample is identified by a number, and the mean value (set to zero 

on the diagram) of the chosen concentration 

ranges is shown. The columns of percent 

frequency include (1) the values of the mean 

interval plus one adjacent interval on each side, 

and (2) the mean plus two adjacent intervals on 

each side. Qualified values of G within two 

intervals of the mean are included in the 

frequency calculations,whereas qualified values 

of N within two intervals of the mean are not. A 

final column denotes the total number of 

analyses of a particular sample.

DISCUSSION

The frequencies of analytical values (not 

including those at the lower limit of detection) 

within the reporting interval containing the 

mean value plus or minus one and two adjoining 

intervals have respective norm values of approximately 83 percent and 96 percent. These 

values are consistent for a variety of geologic 

materials and show no appreciable difference 

between elements or their concentration ranges 

regardless of the variation apparent in some of 

the histograms. Some of the more extreme 

outlying values and some of the consequent 

variation may be due to misplaced decimals, 

inadvertent zeros, or errors made in transcribing the more than 81,000 determinations included in the study.

When the concentration levels of the elements 

are at or near the detection limit of the method, 

the precision tends to be lower. Much of this can
be attributed to N (not detected) values being 

reported for the low concentration levels. For 

concentration levels at or near the detection 

level, such elements as As, La, Nb, Sn, Sr, Zn, 

and Zr were not detected by the analyst more 

than 25 percent of the time. Factors causing this 

could be (1) differences in instrumentation, (2) 

inconsistencies in the analytical procedure, (3) 

inexperienced spectrographers, or, possibly 

more important, (4) detection levels set too low 

for these elements. Four elements Mn, Ag, As, 

and Cu show a distinct bimodal distribution 

in the frequency diagrams at the lowconcentration levels. These bimodal distribution patterns are indicative of an analyst's 

inability to visually distinguish between concentration steps in the spectrographic standards at the lower levels.

The precision of the six-step semiquantitative 

spectrographic method is equal to and even 

exceeds in certain instances the precision of 

other studies (Myers and others, 1961; Barnett, 

1961) developed under more stringent laboratory conditions. The authors feel the precision of 

the method is more than adequate for the 

intended purpose of the procedure. Until newer 

or more sensitive multielement methods are 

developed, the six-step semiquantitative spec- 

.trographic method holds a unique position as

one of the most useful and effective datagathering reconnaissance tools in geochemical 

exploration.

REFERENCES CITED

Allcott, G. H., and Lakin, H. W., 1974, Statistical summary 

of geochemical data furnished by 85 laboratories for six 

geochemical exploration reference samples: U.S. Geol. 

Survey Open-File Kept, 103 p.

 1975, The homogeneity of six geochemical exploration reference samples, pt. 1, in Geochemical Exploration 1974: Fifth Internal Geochem. Explor. Symposium, p. 659.

Barnett, P.R., 1961, An evaluation of whole-order, Va-order, 

and 1/3-order reporting in semiquantitative spectrochemical analysis: U.S. Geol. Survey Bull. 1084-H, p. 

183-206.

Canney, F. C., Myers, A. T., and Ward, F. N., 1957, A truckmounted spectrographic laboratory for use in geochemical exploration: Econ. Geology, v. 52, no. 3, p. 289-306.

Grimes, D. J., and Marranzino, A. P., 1968, Direct-current 

arc and alternating-current spark emission spectrographic field methods for the semiquantitative analysis of 

geologic materials: U.S. Geol. Survey Circ. 591, 6 p.

Myers, A. T., Havens, R. G., and Dunton, P. J., 1961, A 

spectrochemical method for the semiquantitative analysis of rocks, minerals, and ores: U.S. Geol. Survey Bull. 

1084-1, p. 207-229.

Ward, F. N., Lakin, H. W., Canney, F. C., and others, 1963, 

Analytical methods used in geochemical exploration by 

the U.S. Geological Survey: U.S. Geol. Survey Bull. 

1152, p. 92-94.
-4 -3-2-1 0 1 234 5 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (percent) One interval Two Intervals analyses

6 0.5

11 3

4 10

98 147

96 136

98 152

FIGURE 1. Frequency diagram and tabular summary for iron in selected experimental samples; Fe

detection level (0.05) in percent.

-2-1 0 1 234 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (percent) One interval Two Intervals analyses

0.5

1

5

98 126

99 102

97 136

FIGURE 2. Frequency diagram and tabular summary for magnesium in selected experimental 

samples; Mg detection level (0.02) in percent.
40 rr i 1 i i i i | i i i i i i i i i I 

. T 0.07

30

20

10

-3 -2-1 0 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (percent) One interval Two intervals analyses

0.07 95 88

93 152

FIGURE 3. Frequency diagram and tabular summary for calcium in selected experimental samples;

Ca detection level (0.05) in percent.

-4 -3 -2-1 0 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (percent) One interval Two intervals analyses

.05

17

129

102

FIGURE 4. Frequency diagram and tabular summary for titanium in selected experimental samples;

Ti detection level (0.002) in percent.
40

30

20

10

^2 3 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two Intervals analyses

6

14

2

15

1,500

3,000

70

86

90

86

100

98

149

113

152

FIGURE 5. Frequency diagram and tabular summary for manganese in selected experimental 

samples; Mn detection level (10) in ppm. Box indicates qualified value N or G.

-3 -2 -1 O 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

20

11

13

0.7

10

200

91

85

84

95

97

95

88

136

134

FIGURE 6. Frequency diagram and tabular summary for silver in selected experimental samples; Ag 

detection level (0.5) in ppm. Box indicates qualified value N or G.
40n-r

-4 -3 -2-1 0 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two Intervals analyses

300

500

2,000

149

141

FIGURE 7. Frequency diagram and tabular summary for arsenic in selected experimental samples; As 

detection level (200) in ppm. Box indicates qualified value N or G.
-2-1 0 1 2 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two Intervals analyses

137

149

FIGURE 8. Frequency diagram and tabular summary for gold in selected experimental samples; Au 

detection level (10) in ppm. Box indicates qualified value N or G.
-4 -3 -2-1 0 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two Intervals analyses

10

50

300

82

75

88

99

136

140

FIGURE 9. Frequency diagram and tabular summary for boron in selected experimental samples; B 

detection level (10) in ppm. Box indicates qualified value N or G.

10
-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

Number Concentration (ppm) One interval Two Intervals analyses

20

500

1,500

113

137

FIGURE 10. Frequency diagram and tabular summary for barium in selected experimental samples; 

Ba detection level (20) in ppm. Box indicates qualified value N or G.

11
-4 -3 -2-1 0 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two Intervals analyses

96

100

96

141

97 151

FIGURE 11. Frequency diagram and tabular summary for beryllium in selected experimental 

samples; Be detection level (1) in ppm. Box indicates qualified value N or G.

12
I III I I I I I I I I l.»-l-<-l.l.JJ_M I I I I I I | I I I I I I I I I | 

'\ ' """ *

-2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two Intervals analyses

15

50

500

99

129

96

FIGURE 12. Frequency diagram and tabular summary for bismuth in selected experimental samples; 

Bi detection level (10) in ppm. Box indicates qualified value N or G.

-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two Intervals analyses

50

100

134

136

FIGURE 13. Frequency diagram and tabular summary for cadmium in selected experimental samples; 

Cd detection level (20) in ppm. Box indicates qualified value N or G.

13
-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

16

18

14

,7

30

150

91

83

78

97

98

91

96

103

113

FIGURE 14. Frequency diagram and tabular summary for cobalt in selected experimental samples; Co 

detection level (5) in ppm. Box indicates qualified value N or G.

14
I ' I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I

1 2 3 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two Intervals analyses

10

300

3,000

83

136

113

FIGURE 15. Frequency diagram and tabular summary for chromium in selected experimental 

samples; Cr detection level (10) in ppm. Box indicates qualified value N or G.

15
-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two Intervals analyses

7

50

5,000

103

152

134

FIGURE 16. Frequency diagram and tabular summary for copper in selected experimental samples; 

Cu detection level (5) in ppm. Box indicates qualified value N or G.

-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two Intervals analyses

6

9

11

20

50

100

52

89

92

52

98

98

88

152

136

FIGURE 17. Frequency diagram and tabular summary for lanthanum in selected experimental 

samples; La detection level (20) in ppm. Box indicates qualified value N or G.

16
60

50

40

30

20

10

,. .^ti^frr:.......ir.TT».... i......... i......... i......... i....... TTrrri

-4

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One Interval Two intervals analyses

7

20

300

152

136

97

FIGURE 18. Frequency diagram and tabular summary for molybdenum in selected experimental 

samples; Mo detection level (5) in ppm. Box indicates qualified value N or G.

I ' I I l I I I I I | I I I l I I I I l | I I l I I l I I i | I I I I I I I I I | I I I I I I I I I [ I l I I M l i I |

-3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample rercen 

Number Concentration (ppm) One interval

Percent frequency Total

Two intervals analyses

50 75 153

FiGURE 19. Frequency diagram and tabular summary for niobium in selected experimental samples; 

Nb detection level (10) in ppm. Box indicates qualified value N or G.

17
60

50

40

Et 30

20

10

-4 -3 -2-1 0 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

5

30

1,000

136

151

112

FIGURE 20. Frequency diagram and tabular summary for nickel in selected experimental samples; Ni 

detection level (5) in ppm. Box indicates qualified value N or G.

18
-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (opm) One interval Two intervals analyses

20

500

1,500

153

129

137

FIGURE 21. Frequency diagram and tabular summary for lead in selected experimental samples; Pb

detection level (10) in ppm.

-4-3-2-1 0 1 234 5 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

5 100

9 300

13 3,000

86 141

96 152

98 134

FIGURE 22. Frequency diagram and tabular summary for antimony in selected experimental 

samples; Sb detection level (100) in ppm. Box indicates qualified value N or G.

19
-4 -3 -2-10123 

ONE SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

139

135

FIGURE 23. Frequency diagram and tabular summary for scandium in selected experimental

samples; Sc detection level (5) in ppm.

20
-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

10

15

200 94

126

133

140

FIGURE 24. Frequency diagram and tabular summary for tin in selected experimental samples; Sn 

detection level (10) in ppm. Box indicates qualified value N or G.

21
-3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

7

1

11

100

200

500

75

93

96

76

99

98

126

139

136

FIGURE 25. Frequency diagram and tabular summary for strontium in selected experimental 

samples; Sr detection level (100) in ppm. Box indicates qualified value N or G.

22
-3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

20

500

7,000

97

96

100

136

134

136

FIGURE 26. Frequency diagram and tabular summary for vanadium in selected experimental 

samples; V detection level (10) in ppm. Box indicates qualified value N or G.

-3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

50

95

128

151

FIGURE 27. Frequency diagram and tabular summary for tungsten in selected experimental samples; 

W detection level (50) in ppm. Box indicates qualified value N or G.

23
-4 -3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

99

50 140

136

FIGURE 28. Frequency diagram and tabular summary for yttrium in selected experimental samples; Y

detection level (10) in ppm.

50rr

-3 -2-10123 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

200

500

3,000

83

141

137

FIGURE 29. Frequency diagram and tabular summary for zinc in selected experimental samples; Zn 

detection level (200) in ppm. Box indicates qualified value N or G.

24
-4 -3 -2-1 0 1 23 

ONE-SIXTH ORDER SPECTROGRAPHIC INTERVALS WITH MEAN SET AT ZERO

Sample Percent frequency Total 

number Concentration (ppm) One interval Two intervals analyses

4

10

2

10

50

500

46

90

54

48

97

90

15Z

128

153

FIGURE 30. Frequency diagram and tabular summary for zirconium in selected experimental 

samples; Zr detection level (10) in ppm. Box indicates qualified value N or G.

25 k U.S. GOVERNMENT PRINTING OFFICE 1976 777-034