Modal Analysis
This menu item is used to perform a quantitative modal analysis of unknown compositions, based on a group of modal phases that are defined by selecting standard compositions from a standard database. Any database of standard compositions may be used to define the phases, since the modal groups thus defined are stored within each standard database and may be recalled for use with subsequent data sets.
Typically this procedure is performed on a large set of compositional data acquired using multiple traverses or gridded locations that are statistically representative of the material in question. The input file must contain the oxide or element symbols for each column of data enclosed in double quotes, in the first line of the data file. The file must not contain a totals column.
The number of matches and abundance of each phase in the group will be tabulated and the average and standard deviation of each phase calculated. A sample output is shown here for a silicate modal analysis :
Modal Group 1 silicate
Minimum Total = 95
Phase 1 plag
Minimum Vector = 4
End Member = Feldspar
301 albite (cazadero)
306 anorthite (Grass Valley) U.C.#16706
Phase 2 alka
Minimum Vector = 4
End Member = Feldspar
301 albite (cazadero)
374 orthoclase MAD-10
Phase 3 oliv
Minimum Vector = 4
End Member = Olivine
263 Fe2SiO4 (synthetic fayalite)
273 Mg2SiO4 (magnesium olivine) synthetic
Phase 4 opyx
Minimum Vector = 4
End Member = Pyroxene
350 enstatite 25-25
469 hypersthene, johnstown USNM #746
Phase 5 cpyx
Minimum Vector = 4
End Member = Pyroxene
358 diopside (Chesterman)
453 augite, kakanui USNM 122142
Line Vector Phase End - Member Sum SiO2 FeO CaO Al2O3 MgO Na2O
1 .30 opyx Wo 8. En 65. Fs 27. . 98.70 52.80 17.70 4.06 .44 23.51 .19
2 .93 opyx Wo 3. En 47. Fs 50. . 98.48 50.08 29.90 1.44 1.23 15.78 .05
3 2.14 opyx Wo 2. En 82. Fs 16. . 98.94 50.55 12.18 1.22 .62 34.37 .00
4 .24 oliv Fo 84. Fa 16. . . 99.61 37.18 15.45 .09 .33 46.56 .00
5 .98 opyx Wo 1. En 87. Fs 13. . 99.20 54.66 9.28 .29 .09 34.88 .00
6 ------ ------ . . . . 82.11 40.66 7.28 .21 .08 33.88 .00
7 .05 oliv Fo 84. Fa 16. . . 100.08 38.55 15.79 .06 .55 45.13 .00
8 .00 oliv Fo 85. Fa 15. . . 101.46 40.37 14.91 .08 .00 46.10 .00
9 .05 oliv Fo 83. Fa 17. . . 100.00 38.62 16.39 .06 .00 44.93 .00
10 .06 oliv Fo 83. Fa 17. . . 100.16 38.47 16.23 .03 .29 45.14 .00
11 .02 oliv Fo 96. Fa 4. . . 99.99 41.07 4.30 .00 .56 54.06 .00
12 .68 opyx Wo 1. En 87. Fs 12. . 99.08 55.33 8.44 .70 .16 34.45 .00
13 .08 oliv Fo 83. Fa 17. . . 97.86 37.46 15.97 .01 .03 44.39 .00
14 .07 oliv Fo 84. Fa 16. . . 100.50 38.51 15.58 .32 .40 45.69 .00
15 .01 oliv Fo 84. Fa 16. . . 101.09 39.76 15.53 .05 .00 45.75 .00
16 .12 oliv Fo 84. Fa 16. . . 98.92 37.73 15.36 .02 .03 45.78 .00
17 .00 oliv Fo 84. Fa 16. . . 101.15 40.03 15.59 .01 .00 45.52 .00
18 5.64 ------ . . . . 97.77 48.90 29.60 7.96 3.86 6.87 .58
19 17.73 ------ . . . . 98.53 51.92 31.90 .00 1.85 .00 12.86
20 .59 cpyx Wo 42. En 48. Fs 10. . 98.64 52.92 6.20 19.97 2.80 16.40 .35
21 ------ ------ . . . . 69.50 38.92 6.20 11.97 1.80 10.40 .21
22 .17 oliv Fo 83. Fa 17. . . 100.64 37.94 16.66 .04 .02 45.98 .00
23 .09 oliv Fo 83. Fa 17. . . 97.01 36.81 16.07 .26 .28 43.59 .00
24 .05 oliv Fo 84. Fa 16. . . 100.08 38.55 15.79 .06 .55 45.13 .00
25 .00 oliv Fo 85. Fa 15. . . 101.46 40.37 14.91 .08 .00 46.10 .00
26 .02 alka Ab100. An . Or . . 98.65 67.84 .05 .00 19.65 .04 11.07
27 .00 plag Ab 85. An 15. Or . . 100.33 64.10 .17 3.26 22.66 .25 9.89
28 .05 oliv Fo 83. Fa 17. . . 100.00 38.62 16.39 .06 .00 44.93 .00
29 .06 oliv Fo 83. Fa 17. . . 100.16 38.47 16.23 .03 .29 45.14 .00
30 .08 oliv Fo 83. Fa 17. . . 97.22 37.16 16.25 .05 .02 43.74 .00
31 .00 plag Ab 91. An 9. Or . . 100.44 66.12 .00 2.02 21.66 .00 10.64
32 .07 oliv Fo 83. Fa 17. . . 100.39 38.57 16.57 .02 .00 45.23 .00
33 .97 oliv Fo 83. Fa 17. . . 99.96 42.15 14.88 1.17 1.82 39.94 .00
34 .08 oliv Fo 82. Fa 18. . . 100.27 38.28 17.31 .05 .00 44.63 .00
35 .01 oliv Fo 83. Fa 17. . . 97.14 38.14 15.69 .23 .25 42.83 .00
36 1.90 oliv Fo 80. Fa 20. . . 98.26 43.94 15.86 1.00 1.01 36.45 .00
37 .07 oliv Fo 82. Fa 18. . . 99.87 38.17 17.35 .05 .00 44.30 .00
38 .66 opyx Wo 9. En 76. Fs 15. . 96.47 50.60 9.91 4.57 4.07 27.32 .00
39 .77 opyx Wo 1. En 83. Fs 16. . 98.26 53.16 11.34 .42 .59 32.75 .00
Results of Modal Analysis
InputFile : C:\SOURCE\PROBEWIN\modal.dat
OutputFile : C:\SOURCE\PROBEWIN\modal.out
Date and Time: 5/22/97 9:29:44 PM
Group Name : silicate
Total Number of Points in File : 39
Valid Number of Points in File : 37
Match Number of Points in File : 35
Minimum Total for Valid Points : 95.00
Percentage of Valid Points : 94.9
Percentage of Match Points : 89.7
Phase #Match %Total %Valid %Match AvgVec
plag 2 5.1 5.4 5.7 .00
End - Member Sum SiO2 FeO CaO Al2O3 MgO Na2O
Average: Ab 88. An 12. Or . . 100.38 65.11 .09 2.64 22.16 .13 10.27
Std Dev: 4. 4. . . .08 1.43 .12 .88 .71 .18 .53
Phase #Match %Total %Valid %Match AvgVec
alka 1 2.6 2.7 2.9 .02
End - Member Sum SiO2 FeO CaO Al2O3 MgO Na2O
Average: Ab100. An . Or . . 98.65 67.84 .05 .00 19.65 .04 11.07
Std Dev: . . . . .00 .00 .00 .00 .00 .00 .00
Phase #Match %Total %Valid %Match AvgVec
oliv 24 61.5 64.9 68.6 .18
End - Member Sum SiO2 FeO CaO Al2O3 MgO Na2O
Average: Fo 84. Fa 16. . . 99.72 38.96 15.46 .16 .27 44.88 .00
Std Dev: 3. 3. . . 1.31 1.67 2.47 .30 .42 2.93 .00
Phase #Match %Total %Valid %Match AvgVec
opyx 7 17.9 18.9 20.0 .92
End - Member Sum SiO2 FeO CaO Al2O3 MgO Na2O
Average: Wo 4. En 75. Fs 21. . 98.45 52.45 14.11 1.81 1.03 29.01 .03
Std Dev: 4. 15. 14. . .93 2.10 7.60 1.76 1.39 7.24 .07
Phase #Match %Total %Valid %Match AvgVec
cpyx 1 2.6 2.7 2.9 .59
End - Member Sum SiO2 FeO CaO Al2O3 MgO Na2O
Average: Wo 42. En 48. Fs 10. . 98.64 52.92 6.20 19.97 2.80 16.40 .35
Std Dev: . . . . .00 .00 .00 .00 .00 .00 .00
Creating an Input File