Relation of Infrared Spectra and Chemical Analysis for Some Chlorites and Related Minerals W. M. TUDDENHAM and R. J. P. LYON Kennecotf Research Center, Salt lake City, Utah
b An unknown chlorite mineral sample can be classified, from an infrared study alone. By relating the infrared absorption spectra to the chemical analysis of a series of 21 chlorites and related minerals, both the degree of substitution of aluminum for silicon ( Y number) and the total iron content o f the mineral can b e estimated from infrared data. The structural type also can be deduced readily from the infrared curve. There i s a possibility of a structural modification as Y values increase beyond 1.2.
C
are frequently found in areas of altered rocks near ore bodies, giving a n over-all greenish hue for appreciable distances outn ard from the iiietallized centers. Despite their n idespread occurrence, little use has been made of the chlorites as units in the mapping of metal distribution This has been largely due to the difficulty of Classifying the members, and many norkers have felt that a simple classification method nould make possible more diagnostic use of these minerals. If one could easily define a set of minerals diagnostic of the presence of ore (f3), the economic implications n ould he obvious. A stud) of a suite of purified chlorites and related minerals was recently completed a t the University of Utah b y Phillips ill). TI ho made detailed optical, x-ray diffraction, and differential thermal annl!xs of 26 chlorite samples and evoh ed a classification for them based on calcdations from chemical data. These sainplcs n-ere analyzed a t the Kennecott Research Center b y infrared techniques: to determine if a more rapid nipthod of classification could be established. Phillips’ data have been of singular importance in relating infrared spectra to the chemistry of the samples. Structurally, nithin the group of minerals studied, there are two polymorphous groups-the norinal chlorites nhich have alternating “mica-type” and “brucite-type” sheets; and a second group in which the members have a “kaolinite-type” structure. Normal chlorites, as seen in Figure 1, have a repetition of the basal plane e w r y 14 A., and thus usiially are termed 14 A. HLORITES
(Al+3) for silicon (Si+4) in the basal, tetrahedrally coordinated layer. The measure of this substitution in terms of four silicon ions is usually calculated from chemical analysis and is expressed as
chlorites. The kaolinite-type, which repeat the basal plane every 7 A., are termed 7 A. chlorites, “septechlorites,” or sometimes clay chlorites (9), because of the kaolinite nature of the crystal lattice. Brindley and Robinson (3) consider it desirable to base classification on some structural scheme; hence the kaolinite-type structures should be omitted from the chlorite group and associated Kith some other group of minerals. The almost simultaneous nork of Kelson and Roy ( I O ) , hon-ever, demonstrated that the two structures are essentially polymorphic forms of the same mineral Tyith stability temperature ranges for each form. This fact, combined with the historic association of amesite, chamosite, antigorite, and cronstedtite with the chlorites, led Phillips to agree with Nelson and Roy that i t is desirable to have a classification which n-ill apply to both structures. The prefix “septe” Jyas suggested by Nelson and Roy to designate the 7 A. structure, and Phillips adhered to this nomenclature. This paper follow, in general, the terminology applied b y Phillips to the 21 samples. Both type structures are easily modified b y ionic substitution of aluminum
+ Y Al+3 = 4(Si, Al)
(4 - Y)Si+4
here Y may have any value from 0 to 2. Ionic substitution in the octahedrally coordinated layers is even more pronounced and numerous trivalent and divalent ions replace the magnesium(I1) of the mica or kaolinite-type layers. The most noticeable ion is iron(I1) ferrous ion, but aluminum, nickelous, chromous, manganous, and ferric ions are known to occur. The Y substitution of aluminum(II1) for silicon(1V) in the tetrahedral layers, and that of iron(I1) for magnesium(I1) in the octahedral layers are the most common substitutions and are diagnostic for classifying chlorites according to systems such as those of Hey (6). If the value of these two important substitutions in chlorites can be determined from the characteristics of the infrared absorption curve. a much simpler method of distinguishing the many chlorites from one another will have been demonstrated. I\
Table I. Original Name, Locality of Samples Studied, and Phillips‘ Proposed Name Based upon Chemical Analysis, Arranged in Increasing Y Number
Phillips’ Original Proposed Same Name Locality Zlatousk, Siberia Delessite 1 Leuchtenbergite Diabantite Bingham, Utah 2 Chlorite Lenni, Pa. Delessite Lennilite 3 Diabantite Newington, Conn. 4 Diabantite Clinochlore Langban, h e d e n Penninite 5 Clinochlore Bremter, N . Y. Clinochlore 6 Kochubeite Iiammererite Sislriyou City, Calif. 7 Clinochlore Leuchtenbergite Gabbs, Nev. 8 Sheridanite Prochlorite Hartford City, Md. 9 Daphnite Thuringite Dona Ana City, N. M. 10 Sheridanite Prochlorite 11 Chester, Vt. Prochlorite Chlorite Southbury, Conn. 12 Thuringite Ripidolite Goscheneralp, Switzerland 13 Sheridmite Sheridanite Miles City, hlont. 14 Prochlorite Simplon Tunnel, Switzerland Prochlorite 15 RhodophylliteQ Clinochlore Eldorado City, Colo. 16 Corundophilite Corundophilite Chester, Xlnss. 17 Septechlorite Kammererite Lancaster, Pa. 18 Septeantigorite Antigorio Italy Antigorite 19 Septekammererite’ Kammererite Selukue, Rhodesia 20 Septeamesite Amesite Chester, Mass. 21 a No. 16 should be designated as a chromian corundophilite in agreement n-ith the assigned Y number of 1.53 and No.20 is an iron-poor berthierine ( 7 ) . Sample YO.
A.
VOL. 31, NO. 3, MARCH 1959
0
377
Table II.
Names and Reduced Analyses of Chlorite Samples Increasing Y Number
the grinding operation was done under alcohol. This modification of infrared curves by excessive grinding has been noted in this laboratory and by other investigators ( 4 ) with many minerals having structural features comparable to the chlorites.
( I I ) , Arranged in
0.84 . . . 3 . 7 5 . . . . . . 0 . 0 3 7.41 0 . 5 5 0 . 1 9 . . . 2.94 1.29 0 . 0 1 . . . 0.12 7.10 0 . 5 7 0 . 4 9 . . . 4 . 1 4 0.05 . . . . . . 0.02 8.74 0.62 0.30 . . . 2 , 1 4 1 . 7 8 . . . . . . . . 10.30 0.73 0.13 5.21 0.06 ... 8.55 1.03 0.23 . . . 4 . 7 0 0.'16 . . . ... 9.00 1.09 0.08 0.25 4.75 . . . . . . 0 . 0 1 . . . 9 . 4 0 1.16 0.06 . . . 4.62 . . . . . . . . . 9 . 1 1 1.18 0 . 1 5 . . . 4 . 2 6 0.50 0 . 0 1 . . . 0.02 8.06 1 . 2 2 0.50 . . . 0 . 8 2 2.93 0 . 0 8 . . . 0 . 0 3 7.93 1.26 0.16 . . . 3.68 1 . 1 5 . . . . . . 0.08 7 . 3 5 1.28 0.49 . . . 2.23 1.90 . . . . . . 7.10 1.35 1.60 . . . 1.59 1.40 0.04 . . . . . . 8.04 1.38 0.04 . . . 4.24 . . . . . . . . . 8.79 1.44 0.39 1 . 7 5 2.41 . . . 0 . 0 1 8 . 3 5 1.50 0.29 4.38 0.08 . . . 0 . 0 1 . . . 8.41 1.53 0.24 . . . 2 . 8 5 1 . 3 4 0.08 . . . 0.01 8.64 1 . 5 7 . . . 0.04 4.60 0.08 0.02 . . . 6.75 0 . 1 5 . . . 5.14 0 . 3 3 0.01 . . . 8 . 0 3 0.06 0.06 5.12 . . . . . . 0 . 0 3 . . . 8.31 0.77 0.12 3.39 0.61 . . . . . . . . . 7.65 1 . 9 5 0 Corrected in calculations, for 10% quartz. b Sample classed as a septechlorite on basis of x-ray differential thermal analysis and infrared results despite apparent'ly excessive Si content. 1 2 3 45 5 6 7 8 9 10 11 12 13 14 15 16 17 18* 19 20 21
3.45 3.43 3.38 3.27 2.97 2.91 2.84 2.82 2.78 2.74 2.72 2.65 2.62 2.56 2.50 2.47 2.43 4.67 3.94 3.23 2.05
1.53 1.89 1.28 1.27 1.54 1.65 1.57 2.06 2.28 2.60 2.44 2.84 2.21 2.79 2.71 2.64 2.77 0.34 0.28 1.05 3.94
It was observed that the samples could be arranged on the basis of spectra, into one of the folloving general classifications:
I. Those with only one strong absorption band between 9.3 and 11.0 microns and two clearly visible absorption bands between 2.6 and 3.0 microns. 11. Those m-ith multiple absorption bands between 9.3 and 11.0 microns and two clearly visible absorption bands between 2.6 and 3.0 microns. 111. Those with multiple absorption bands between 9.3 and 11.0 microns and three clearly visible absorption bands between 2.6 and 3.0 microns. The septechlorites were in this classification.
tons' pressure. The absomtion curves were bbtained using a Perkin-Elmer Model 21 spectrophotometer with rock salt optics. Dry grinding the chlorite samples in preparation for infrared analysis often altered the chlorite so as t o modify the resulting absorption curve sharply. T o avoid this difficulty,
EXPERIMENTAL
The original names, locations, and Phillips' name assignments based upon the chemical analyses of the samples are given in Table I. Of more fundamental importance in this study are the analyses of the samples based upon cations per 18 oxygens which are given in Table 11. Some original samples were omitted from this study, because of impurities that became evident upon infrared examination. Infrared absorption spectra were obtained with potassium bromide disks containing 0.25y0of the sample in question. These disks mere prepared by adding 2.50 mg. of a preground sample to 1.00 gram of potassium bromide (Harshaw infrared quality), blending with a Wig-L-Bug amalgamator, weighing out enough of the blend to form a 12-mm. diameter disk of the desired thickness, and pressing in a vacuum die under 12.5
4 O"2 OH'
RESULTS
The wave lengths of the absorption bands for the samples in the 2- to 15.5micron region are listed in Table 111. The weak absorption bands listed are considered to be of diagnostic significance for pure samples only.
Y
Y
1.50
4 0" 2 OH' 6 Mp'.
4 0" 2 OH'
6 OH'
A.
A.
6 0" 4 Si""
6 0" 4 si*-
40" 2 OH'
4 0" 2 OH' C
6 Ma** 4
6 Mg"
0" 2 0 "
6 OH'
4 S!,.'"
A
Figure 1. A. 6.
378
e
E
The two chlorite structures
Normal chlorite or 14 A. structure Kaolinite type or 7 A. structure
ANALYTICAL CHEMISTRY
I
9
10
I
I
I
I
II
9
IO
I1
WAVE L E N G T H
P
Figure 2. Infrared absorption curves in 9- to 1 1 micron region
AXES
6 0
SERIES B I
-
Effect of decreasing ratio, Y, of substitution of AI for Si in tetrahedral positions in the crystal lattice of the magnesian chlorite series A. Total Fe per 18 0-2,0 to 0.8 B . Total Fe per 1 8 O-', 2.0 to 2.8 Curves are displaced vertically
VARIATIONS WITH RESPECT TO Y NUMBER
correspond with Groups I and 11, respectively, with the exception of sample 1 and the kaolinite-type structures. Samples 1 and 13 showed greater deviations from the curves for their respective groups, but were still in approximate agreement with the other results (see discussion).
Cpon comparing the spectral data of the individual samples, the most significant absorption bands were seen to occur in the 2.6- to 3.0- and the 9.0- to 10.5-micron regions. When the curves werp arranged in order of increasing Y number, an interesting picture became evident. The absorption patterns in the 9.0- t o 10.5-micron region varied from t n o major absorption bands a t low Y L alue, through three absorption bands. thence to one absorption band, and finally to tlyo absorption bands a t a high I' ~ a l u e . This phenomenon \\as found to depend only upon the Y valur :ind it illustrated in Figure 2 for each of t n o different ranges of total iron coni rntrations n-ithin the molecule- .iltliougli the u - a e~lengths of the major ahsorption bands are different for w n p i c s n ith comparable Y values in thP high- and lon-iron ranges, the curve shnpc'. rcmarkablj similar. ~
i
(
KAOLINITE-TYPE STRUCTURES
The infrared spectra in the 2.6- to 3.0-micron region are presented in expanded form in Figure 4, as a comparison, for three kaolinite-type structures and one normal chlorite. These samples were classified into 14 A. and 7 A. forms by x-ray diffraction measurements. (Septe)antigorite (19) has a pronounced absorption band a t 2.73 microns which is relatively weak in (septe)kammererite (20),and has shifted to 2.78 microns in the spectrum of (septe)amesite (21). This absorption band is fxtremely weak in the curve of the normal chlorite, prochlorite
1
number 12. Differential thermal analyses curves of these samples showed a similar progressive modification of the cur\-es from (septe)antigorite to prochlorite. The significance of these results is discussed below. DISCUSSION
OF RESULTS
Figure 3 shows that a definite pattern is followed as one compares infrared curve shapes in the 10-micron region with the Y number. This can be of distinct value in determining the location of a sample in the chlorite series. I n addition, the position of the absorption band near 10 microns approximates, in trvo distinct series, the total iron content. Samples \J-ith I' numbers greater than 1.2 also showed a weaker correlation betxeen total iron and the absorption band a t about 13 microns. Pure samples are, of course, essential in this type of work. Appreciable contamination b y quartz. feldspar, or other minerals n hich absorb
VARIATION WITH TOTAL IRON 4.0
The curves in Figure 2 show a variation in the position of the maximum absorption band which is not related to the Y values. Figure 3 was obtained, upon plotting the n-ave length of the absorption band nearest 10 microns us. total iron. Excluding the kaolinitetype structures as special cases, the data fell into tv-o distinct series Fvith the measured wave lengths within each series tpnding to increase with the total iron for the sample. On checking the sample numbers in the two series against their analyses in Tahle 11. the t n o series in Figure 3 n-ere found to
Table Ill. Sample 1 2 0
3
15 16 17
18
*
2.75vn- 2.80m 2 . 7 3 ~ 2.81m 2 7 ' h r L80m .. . 2.77m
2.90m
2.94ni 2.92ni
2.73m 2.7Sm
9 10 11 12 13 14
0
-1
a
2.0
IO I-
5
1.0
(r
10.0
10.1 WAVE L E N G T H
Wave Length Region, Microns 10 through 11
20 21
s
a
Group I samples Group II samples Group 111 samples (septe)chlorites
3.0
0: W
6 through 9
1I ) C
5 6 7
0
E
10.2
10.3
p
Positions of Infrared Absorption Bands in Chlorite Samples, Arranged in Increasing Y Number
2.88m 2.77m 2.88m 2 72? 2.78m 2.89m '1.73tx2 . i 9 m 2.9Om 2 73vw 2 i 9 m 2.91m '1 7 2 v ~ 2 i 9 m 2.91m 2.75mv 2 , 8 2 m 2 . 9 3 m 2 . 7 2 n r - 2 81m 2.92m 2 75vw 2.81m 2.90m 2 . it5vn- 2.82m 2.92m 2 73vv 2.80m 2.92m 2.75vn- 2.81m 2.91m 2 . 72vw 2.80m 2.90m 2.i5vxv 2.81m 2.90m 2.i2m 2 . 8 2 ~ 2.93m 2.80m 2.92m 2.73m
4
0
0
2 through 5
so.
Figure 3. Position of maximum absorption peak in vicinity of 10 microns vs. total iron
...
2 . i81n 2.81m
2.89m 2.92m
6.12~9 . 2 5 ~ 6 . 1 0 ~ 9 . 2 5 ~ 9~. 6 0 ~ 6 . 0 8 ~ 9.271%... b
b
6.13-r 9 . 2 5 ~ 9.60m 6 . 1 0 ~ -9~. 2 5 ~ 9.53m 6 . 1 2 ~ 9.25%. 9.60m 6.131%- 9 . 2 5 ~ 9.65, 6 . 1 3 ~ 9 . 2 6 ~ ~. 6 . 15w . . 6 . 1 3 ~ 9.2i;v . . 6 . 1 3 ~ .. . ... 6.12~ ... 6 . 1 3 ~ 9.2ivn... 6 . 1 5 ~ ... ... ...
...
6 . '13w 6 . 1 0 ~ 8.SOm 9.30s 6 . 1 3 ~( 8 3 1 ~ ) 9 32s 8.85~ . . . 9 . 2 3 ~ 9.48m
...
...
...
10.09s 10 08s 10.03s 10.08s 10.02s 10 03s 10 04s 10 13s 10.16s 10 21s 10 l i s
... ,..
, .
.,
...
l5.20m 15.lm 15.25m b * 15.45m 12.18~ . .. 15.25m 12 2m13,25111 i5.l m 15.26m 12 1617 12 14T 13 iiw 15.Om 12,21\r 13.16m 15.10m 1 2 . 6 0 ~ 13.31m l 5 . 1 2 m 12.3 0 ~ 13.18m 15.17m 12 . 3 1 T T 13,18m 15.1Om 1 3 . 4 0 ~ 15.On12 iiw 13.06m l 4 . 8 5 m 1 2 . 3 8 ~ 13.25, 15.06m 12.08W 13.03m 14.89m 12.25, 13.14m 15.13m 1 2 .56in . . . >15.5m 1 2 .93\17 . . . 15.40s
10.12s 10.22s 10.16s 10.17s 10.15s 10.15s 10.01s lo,&
vw = very weak w = weak m Sample contained a small amount of carbonate (absorptions not listed). Sample contained about 10% quartz (absorptions not listed). Sample classed as a septechlorite (see b , Table 11).
=
12.06m 12.31m 12.31~ ... 12.26~ ...
... ...
1 2 ,331%- 12.75, 12.12m 1 2 .S6m
. . .
10.19s
io.&
12 through 15.5
10.40s 11.28m 10.50~ .,. 10.4ow ... 10.58, ... 10.438 ... 10 38s a 10 40s 11 50m 10 38s
..
. . .. . ... .
10.458 10.76m medium
:
... ... ... ...
s
=
strong
15.44s 14.35, (14.8lm)
VOL. 31, NO. 3, MARCH 1959
0
379
strongly in the 9- to 11-micron region, while recognizable elsen here in the infrared pattern, would obscure the true curve shape and affect the Ivave length reading. A similar contamination, holvever, would be unsuspected and yet vitally affect a chemical classification by changing the siliconaluminum ratios. For this information alone, the infrared examination is of great value. A feature of perhaps even more importance is the sudden shift in the position of the 10-micron absorption band as the Y value reaches the vicinity of 1.2. There appears to be a fundamental difference betn-een chlorites with a Y number greater than about 1.2 and those with lower Y values. The cause of this difference is not now apparent, but the phenomenon seems worthy of further investigation. The apparently anomalous result obtained with clinochlore 8 is ascribed to the possibility that it is a transitional form. If one assumes that the iron was originally entirely in the ferrous state ( I 4 ) , then the linear relationships between total iron and peak absorption in Figure 3 might \Tell be expected. The deviations of samples 1 and 13 from the curves in Figure 3 may be related to the high proportion of ferric iron contained in them. This ferric iron may be of either primary or secondary origin. The significance of ferric iron in chlorite has been revien ed recently by Brindley and Gillery (9). They have discussed the complexities of ferric iron substitution in octahedral coordination and have mentioned that the additional possibility of ferric iron substitution in the tetrahedral positions cannot be dismissed entirely. Either type of substitution would definitely modify the infrared absorption spectra of samples so constituted. The theoretical explanation for the absorption bands found in the 2.6- to 3.0-micron region is not entirely clear. Mackay, Wadsn-orth, and Cutler (8) have discussed the correlation of spectra and structure in this region for a number of clay minerals. According to their theories, the hydroxyl groups in a structure will be subject to different degrees of hydrogen bonding depending upon their positions in the lattice. Other lyorkers ( I , 6) have shown that oxygen-hydrogen stretching frequencies, and thus the position of infrared absorption bands, vary ivith the degree of hydrogen bonding, with absorption bands for more strongly hydrogen bonded groups occurring a t longer wave lengths. One could predict, based upon this reasoning and with reference to Figure 1, that all of the chlorites and the kaolinite-type structures n-ould give three distinct absorption bands in the 2.6- to 3.0-micron region. These absorption bands would be assigned to
380
ANALYTICAL CHEMISTRY
I
I
~
2.6
2.8
~~~
3.0
WAVE L E N G T H p
Figure 4. 0-H stretching absorption bands for one 14 A. and three 7 A. chlorites (curves displaced vertically)
the best explanation of the phenomena observed is still questionable. The central absorption band of the group (at 2 microns) was clearly seen for all 14 A. chlorite samples. For the 7 A. chlorites, its strength varied (Figure 4). This wide variation of the relative strength of the absorption bands attributed to the hydroxyl groups for 7 A. chlorites can be coupled with parallel variations in the differential thermal analysis curves as evidence for heterogeneous interlayer mixing of 7 A. and 14 A. forms. Such a conclusion would be supported by Nelson and Roy ( I O ) , who state that, based on differential thermal analysis results, Chester amesite (the locality of sample 21) is a mixture of the two chlorite structures. Similarly, the very weak absorption bands observed a t about 2.73 microns for most of the 14 A. chlorites may be caused by the presence of traces of 7 A. chlorite. ACKNOWLEDGMENT
“inner” hydroxyls, “outer” hydroxyls, and externally bonded water. I n contrast, Roy and Roy (It?), after studying hydrogen-deuterium exchange in clays, stated that their work did not support a simple correlation between absorption in the OH region of the infrared spectra and the x-ray determined structure. They suggest that steric conditions may be of considerable importance in the determination of interatomic distances and that, therefore, distances measured by x-ray techniques may not necessarily be correlatable with the degree of hydrogen bonding. Farmer (4),however, suggests that some of Roy’s results may have been altered b y water reabsorbed by the samples after preparation. I n agreement with Mackay, Wadworth, and Cutler, a careful examination of the expanded curves in the 2.6to 3.0-micron region shoved evidence of three different absorption bands for almost all samples examined, although the short wave length absorption bands were very difficult to distinguish in the case of most of the 14 A. chlorites and could not be distinguished a t all in some cases. On the other hand, this short wa’i’e length absorption band was clearly visible in the spectra of the 7 A. chlorites with low Y numbers and, although TTeakened and shifted to a somem-hat longer wave length, it was also apparent in the case of the (septe)amesite. It is possible that this difference between (septe)amesite and the other (septe)chlorites is a result of a much higher degree of aluminum substitution. The very wide variation in the strengths of the absorption bands given by the 7 A. and 14 A. forms in the 2.6to 3.0-micron region cannot be explained b y simply assigning the absorption bands to inner and outer hydroxyls as above. Whether this is
The authors wish to acknowledge the cooperation of W. R. Phillips and Bronson Stringham in providing the samples used in this study. They thank S. R. Zimmerley, director of research, for his encouragement of the project and the Kennecott Copper Corp. for permission to publish this paper. LITERATURE CITED
(1) Bellamy, L. J., “Infrared Spectra of
Complex Molecules,” p. 285, Wiley, Kew York, 1954. ( 2 ) Brindley, G. W., Gillery, F. H., Am. Mineralogzst 41, 169-86 (1956). (3) Brindley,. G. TV., Robinson, K. “XRay Identification and Crystal ktructures of Clay Minerals,” pp. 173-98, Mineralogical Society, London, 1951. (4) Farmer, V. C., Mineral. U a g . 31, 82945 (1958). (5) Herzberg, G., “Molecular Spectra and Molecular Structure. 11. Infrared and Raman Spectra of Polyatomic Molecules,” pp. 535-7, Van Nostrand, Kew York. 1945. (6) Hey, hl. H., Mineral. Mag. 30, 27792 (1954:. (7) Hey, M. H., private communication. (8) RIackay, T. L., Wadsworth, M. E., Cutler, I. B., U. S. Atomic Energy Comm. Contract Xo. .4T-(49-1)-633, Tech. Rept. 8, (Nov. 1, 1954). (9) Martin, R. T., Proc. 3rd Natl. Conf. on Clays and Clay Minerals, Natl. Acad. Sci. U.S.-Natl. Research Council, Publ. 395 (1955). (10) h’elson, B. TV., Roy, R., Proc. 2nd Satl. Conf. Clays and Clay Minerals, Xatl. Acad. Sci. US-Natl. Research Council, Publ. 327 (1954). (11) Phillips,, W. R., “Crystal Chemical Classification of the Chlorite hlinerals.” Ph. D. thesis, University of Utah, 1954. (12) Roy, ,De ill.Roy, , R., Geochim. et Cosmochzm. Acta 11, 72-8, erals, in press. (14) Winchell, A. N., Am. Mineralogist 21, 642-52 (1936). RECEIVEDfor review March 17, 1958. Accepted October 6, 1958.
