the composition of corrensite compared with saponite, vermiculite, and chlorite suggest that ... Corrensite, Mixed layer, Smectite, Statistical analysis, Vermiculite.
Clays and Clay Minerals, Vol. 32, No, 5, 391-399, 1984.
CRYSTAL CHEMISTRY OF CORRENSITE: A REVIEW MARIA FRANCABRIGATTI1 AND LUCIANO POPPI2 Istituto di Mineralogia e Petrologia dell'UniversitY, via S. Eufemia 19, 41100 Modena, Italy 2 Istituto di Mineralogia e Petrografia dell'UniversitY, Porta S. Donato 1, 40100 Bologna, Italy Abstract--Statistical analyses of chemical data from the literature of corrensite minerals suggest a large compositional variability, more evident in octahedral than in tetrahedral coordination. Mg occupies 4080% of the octahedral sites, with A1 and Fe2+ making up the remainder. Approximately 15-30% of the tetrahedral sites are filled by A1. Despite this compositional variability, distinct fields for the several types of mixed-layer trioctahedral chlorite/trioctahedral swelling layer are not apparent. Statistical analyses of the composition of corrensite compared with saponite, vermiculite, and chlorite suggest that corrensite is an intermediate between trioctahedral chlorite and trioctahedral smectite. If Fe/(Fe + Mg) > 50%, chlorite alone is favored, but with increasing Mg, chlorite appears to transform into corrensite and then, by iron oxidation, into trioctahedral smectite. Despite the chemical variabilitybetween corrensite, chlorite, and saponite, corrensite appears chemically to be a well-defined species. On the other hand, corrensite cannot be characterized chemically on the basis of its swelling component. Thus, the current definition of corrensite as a regular 1:1 interstratification of trioctahedral chlorite and either trioctahedral smectite or vermiculite is appropriate. Key Words--Chemical composition, Corrensite, Mixed layer, Smectite, Statistical analysis, Vermiculite.
INTRODUCTION Clay minerals which yield an X-ray powder diffraction (XRD) reflection at 32 ~ with ethylene glycol or glycerol treatment have been described from a n u m b e r of genetic environments. L i p p m a n n (1954) gave the name corrensite to one of these materials and defined it as a regular 1:1 interstratified trioctahedral chlorite/ swelling chlorite mineral. He subsequently referred to the swelling component as vermiculite (Lippmann, 1956), and later as "expandable layers" (Lippman, 1957, 1976, L i p p m a n n and Johns, 1969). The existence of a "chlorite/swelling layer interstratification" is now generally accepted, hut the swelling component is still not well characterized, mainly because of its variable behavior in standard solvatation and heating treatments (Lippmann, 1954, 1956, 1976; Bradley and Weaver, 1956; Earley et al., 1956; Sudo and Kodama, 1957; Alietti, 1957a, 1957b; Martin Vivaldi and MacEwan, 1960; Sugiura, 1962; A l m o n e t al., 1976; April, 1980; Churchman, 1980). The X R D features of this material can be summarized as follows: the untreated material gives rise to a reflection at 29-31 /~; after the sample is treated with ethylene glycol, this reflection expands to 31-33 /k; after the sample is heated to 550~ the reflection collapses to 23-28 /~ (Bailey et al., 1982). The thermal behavior of this material has also been widely investigated, but the data are difficult to use because the experiments were commonly insufficiently detailed. Usually the chloritic component is suggested by endothermic peaks at 500-600~ and 810-950~ whereas endothermic peaks at 200~ are assigned to the swelling component (Mackenzie, 1972). A review of Copyright 9 1984, The Clay Minerals Society
chemical analyses from the literature also shows a large compositional range for the swelling component of socalled corrensites. Based on the different nature of the swelling component, several definitions ofcorrensite have been proposed. In particular, Galan and Doval (1977) suggested retaining the name corrensite for a regular interstratification ofchlorite/saponite only and assigning two new, distinct names to the regular interstratification of chlorite/swelling chlorite and chlorite/vermiculite. The Nomenclature Committee of The Clay Minerals Society, however, defined corrensite as a 1:1 regular interstratification of trioctahedral chlorite with either trioctahedral smectite or trioctahedral vermiculite (Bailey et al., 1982). A literature review of so-called corrensites shows a large variability in the crystal-chemical features of these materials. In particular, it is not clear, from the chemical point of view, whether all of the so-called corrensites described in literature can be considered as a single mineralogical species. The aim of the present study was to assess the variability of the crystal-chemical features of the materials described in literature as corrensite and to distinguish, if possible, different compositional ranges for the various materials that have been reported. EXPERIMENTAL Chemical analyses (Table 1) and b dimensions (Table 2) of corrensite materials were selected from the literature. Only the analyses where the authors stated the type and degree of impurities present were considered, and among these, only those where the mineral
391
Clays and C t a y M i n e r a b
Brigatti and Poppi
392
Table 1. Source and chemical analyses of selected corrensites. Sample~
SiO2
A1203 Fe203
FeO
TiO2 MnO
CaO
MgO
1C/Sap 2C/Sap 3 C/Sap
36.12 39.04 30.38
13.67 15.32 24.21
2.14 13.86 0.11
6.85 5.57 2.34
0.23 0.13
1.70 0.30 0.15
25.16 25.23 26.31
0.37 0.68 0.29
4 C/Sap
32.20
18.10
0.23
1.03
0.06
0.18
31.79
5 C/Sap
33.28
21.61
0.66
1.11
0.21
2.52
6C/Sap
34.33
14.94
0.15
0.63
0.04
7 C/M
43.1
16.6
6.32
0.03
8 C/V 9 C/V 10C/V
32.96 39.45 41.20
17.07 14.16 12.1
2.79 21.97 1.74
8.68 9.85 0.39
IIC/M 12 C/Sap
42.19 33.44
17.00 14.33
8.98 1.66
7.43 3.68
13C/Sap
36.7
9.1
14 C/Sap
35.73
14.05
15 C/Sap 16 C/Sap 17C/V 18C/Sap 19C/Sap 20C/Sap 21C/Sap 22 C/Sap
34.72 35.59 33.90 33.57 31.91 35.73 34.65 36.76
23C/Sap 24C/Sap 25C/SC 26C/M 27C/M 28 29 30 31 32 33 34 35 36 37 38
0.47 0.04 0.20 0,16
H20-
H20+
0.10
4.81
9.25
0.08
1.93
13.31
0.10
0.13
2.66
13.28
23.23
tr
0.33
5.48
11.57
0.33
32.19
0.11
0.20
3.67
13.18
0.94
17.65
0.52
2.72
0.58 23.01 0.73 13.15 1.4 22.0
0.58 0.68 0.07
0.16
2.63
11.28
0.22
6.80
15.4
1.98 2.83
21.38 22.44
0,32 0.16
0.51 tr
5.50
8.16
2.20
21.7
0.4
0.2
9.5
8.10 7.80
7.40
2.3
0.1
7.17
7.22
0.11
0.11
3.49
18.44
1.20
0.15
4.09
13.94 15.13 17.60 13.60 14.63 14.05 16.09 15.14
11.45 6.65 10.92 8.38 16.45 7.17 1.61 1.12
4.14 9.15 1.20 ll.31 4.41 7.22 1.30 8.02
0.57 0.30
0,20 0.38
0.59 0.77 0.11 0.34 0.03
0.26 0.25 0.11 0.07 0.36
3.37 1.86 1.10 2.20 2.74 3.49 0.77 0.95
16.61 14.76 20,98 12.93 11.56 18.44 20.97 21.71
1.43 1.13 0.67 1.00 1.65 1.20 0.52 0.03
0.30 1.13 0.68 0.80 0.65 0.15 0.10 0.02
5.69 8.34 6.62 7.30 2.92 9.83 5.68 9.68 4.90 10.47 4.09 7.80 6.58 10.88 15.82
40.63 37.16 32.72 48.58 39.94
15.54 14.98 20.28 13.44 33.17
6.92 12.01 1.00 17.85 1.34
5.76 4.11
0.11 0,13 0.06
0.18
0.81 0.34 0.03 1.78 0.74
1.92 1.80 1.97 2.71 1.30
13.21 14.79 24.47 13.14 6.44
0,46 0.27 0.25 0.88 0.52
0.68 0,88 tr 1,61 0.24
7.42 8.41 7.02 8.00 4.39
33.95 34.00 47.4 48.2 49.1 46.0 39.46 35.5 37.2 37.62 34.25
19.20 16.25 20.7 22.7 22.9 24.8 12.59 15.1 15.5 12.27 11.63
0.71 12.60 8.9 8.2 5.72 7.65 0.31 6.7 6.70 2.18 4.21
0.69
tr
0.74 0.37 0.33 0.33 0.26 0.25 0.22 1.32 0.2
0,05 0,28 0.95 1.08 0.96 1.32 0.03 0.67 1.4
0.26
0.04
6.55 11.26 13.95 9.79 9.89 10.6 10.00 10.94 11.20 12.13 18.4 7.30 12.60 14.73
39 C/Sap
34.64
11.35
40 C/Sap
38.43
16.31
C/V C/V AI-C/M A1-C/M A1-C/M A1-C/M C/M C/M C/M C/V C/Sap
10.6
0.73
Na20 K20
6.52 5.12 12.57 6.96 11.64
0.97 0.95 0.64 0.84 0.02 0.13 0.4
0.32 0.01
0.70 0.50 1.3 0.9 1.07 0.99 0.06 1.06 1.0
3.91
0.20
0.12
1.39
26.31 22.16 6.0 6.4 7.87 8.1 24.91 13.2 18.9 27.9 29.26
3.34
3.73
0.44
0.10
1.85
29.30
0.19
0.02
15.03
3.62
5.33
0.36
0.12
0.28
22.77
0.48
1.20
11.10
0.14 13,5
0.08 0.25 0.21 0.17
Reference Alietti (1957a) April (1981) Shirozuet al. (1975) Shirozuetal. (1975) Shirozuet al. (1975) Shirozuet al. (1975) Earleyet al. (1956) Aiietti(1957b) April (1980) Bradley and Weaver (1956) Blatter et aL (1973) Mongiorgiand Morandi (1970) Kimbara and Shimoda (1972) Kimbaraand Shimoda (I 972) Kimbara(1975) Kimbara(1975) Gallitelli (1956) Kimbara(1975) Kimbara (1975) Kimbara(1975) Kimbara (1975) Taguchiand Watanabe (l 973) Seki et al. (1980) Kimbara (1975) Shimoda(1970) Nichols(1970) SudoandKodama (1957) Sugiura(1962) Gallitelli(1959) Pacquet (1968) Pacquet (1968) Pacquet (1968) Pacquet (1968) Takahashi(1959) A l m o n e t aL (1976) Peterson (1961) Melnik (1959) Brigatti and Poppi (1984) Brigatti and Poppi (1984) Brigatti and Poppi (1984)
J C/Sap = chlorite/saponite; C/M = chlorite/montmorillonite; C / V = chlorite/vermiculite; C/SC = chlorite/swelling chlorite; AI-C/M = Al-chlorite/montmorillonite.
c o r r e n s i t e was p r e s e n t in a m o u n t s greater t h a n 70% were selected. T h e c h e m i c a l analyses a n d m i n e r a l o g i c a l d e s i g n a t i o n s as p r o p o s e d b y t h e r e f e r e n c e d a u t h o r s are listed in T a b l e 1, w h e r e i n C / S a p = c h l o r i t e / s a p o n i t e , C/M = chlorite/montmorillonite, C/V = chlorite/ver-
miculite, C / S C = c h l o r i t e / s w e l l i n g chlorite, a n d A1-C/ M = Al-chlorite/montmorillonite. A s s u m i n g the m i n e r a l s to b e i n t e r s t r a t i f i c a t i o n s o f chlorite a n d s o m e t y p e o f smectite, t h e f o r m u l a e w e r e recalculated by: (1) b a l a n c i n g the charges o n t h e basis
Crystal chemistry of corrensite
Vol. 32, No. 5, 1984
393
Table 2. Unit-cell b dimensions of selected corrensites. Sample' 1 7 14 18 36 40
b (A,)
(C/Sap) (C/M) (C/Sap) (C/Sap) (C/M) (C/Sap)
Sample~
9,222 9.252 9.252 9.258 9.240 9.228
4 10 15 20 38
b (,~)
(C/Sap) (C/V) (C/Sap) (C/Sap) (C/Sap)
Samplet
9.215 9.240 9.252 9.258 9.240
6 13 16 21 39
b (A,)
(C/Sap) (C/Sap) (C/Sap) (C/Sap) (C/Sap)
9,215 9,228 9.258 9.216 9.234
Source and symbolism listed in Table 1.
o f 50 n e g a t i v e charges (O20(OH)1o); (2) assigning all o f t h e Si to t e t r a h e d r a l c o o r d i n a t i o n t o g e t h e r w i t h e n o u g h A1 t o b r i n g the total to 8; (3) assigning Ca, Na, a n d K to interlayer p o s i t i o n s o f the swelling c o m p o n e n t ; (4) assigning all t h e residual c a t i o n s to o c t a h e d r a l c o o r -
d i n a t i o n s . T h e recalculated c h e m i c a l f o r m u l a e are liste d in T a b l e 3. C o r r e l a t i o n tests were p e r f o r m e d b y m e a n s o f a B M D 0 2 R stepwise m u l t i p l e - r e g r e s s i o n p r o g r a m . T h e variability o f c h e m i c a l p r o p e r t i e s was s t u d i e d b y
Table 3. Recalculated chemical formulae of selected corrensites. IV Sample~
Si
1C/Sap 2C/Sap 3C/Sap 4C/Sap 5C/Sap 6C/Sap 7C/M 8C/V 9 C/V 10C/V llC/M 12C/Sap 13C/Sap 14C/Sap 15C/Sap 16C/Sap 17C/V 18C/Sap 19C/Sap 20C/Sap 21C/Sap 22C/Sap 23C/Sap 24C/Sap 25C/SC 26 C/M 27C/M 28C/V 29C/V 30 A1-C/M 31A1-C/M 32AI-C/M 33AI-C/M 34C/M 35C/M 36C/M 37 C/V 38C/Sap 39C/Sap 40C/Sap
6.24 5.95 5.22 5.54 5.78 5.95 7.03 5.77 6.24 7.33 6.37 6.24 6.61 6.24 6.14 6.37 5.81 6.25 5.89 6.22 6.47 6.47 6.99 6.49 5.79 7.22 6.53 5.90 5.86 7.68 7.58 7.67 7.18 7.09 6.36 6.63 6.67 5.99 6.06 6.39
I
AI
AI
1.76 1.03 2.05 0.70 2.78 2.12 2.46 1.21 2.22 2.20 2.05 1,00 0.97 2,22 2.23 1.29 1.76 0.88 0.67 1.87 1.63 1.40 1.76 1.39 1.39 0.54 1.76 1.13 1.86 1.04 1.63 1.56 2.19 1.37 1.75 1.24 2.11 1.07 1.78 1.10 1.53 2.01 1,53 1.61 1 . 0 1 2.14 1 . 5 1 1.57 2.21 2.02 0.78 1.58 1.47 4.92 2.10 1.83 2.14 1.16 0.32 3.64 0.42 3.79 0.33 3.89 0.82 3.75 0.91 1.76 1.64 1.55 1.37 1.89 1.33 1.24 2.01 0.39 1.94 0.40 1 . 6 1 1.59
Mg
Fe3+
6.48 5.73 6,74 8.15 6.02 8.31 4.29 6.01 3.10 5.83 4.81 6.24 5.83 4.80 4.38 3.94 5.36 3.59 3.18 4.88 5.84 5.70 3.39 3.85 6.45 2.91 1.57 6.81 5.70 1.45 1.50 1.83 1.89 6.68 3.53 5.02 7.38 7.63 7.65 5.65
0.28 1.59 0.02 0.03 0.09 0.02 0.78 0.37 2.62 0.23 1.02 0.23 1.44 0.94 1.52 0.90 1.41 1.17 2.28 0.94 0.23 0.15 0.90 1.58 0.13 2.00 0.17 0.09 1.64 1.09 0.97 0.67 0.90 0.04 0.90 0.90 0.29 0.56 0.44 0.45
VI Fez+ 0.99 0.71 0.34 0.15 0.16 0.09 1.27 1.30 0.05 0.94 0.58 0.35 1.06 0.61 1.37 0.17 1.76 0.68 1.05 0.20 1.18 0.83 0.60 0.01
Mn
0.02 0.01 0.03 0.01 0.01
Ti
Z
Na
0.03
8.81 8.73 9.24 9.55 8.50 9.43 7.39 9.00 7.90 7.99 8.20 8.47 8.18 7.96 7.66 7.87 8.31 7.88 7.36 8.00 8.34 8.70 7.39 7.66 8.61 6.69 6.78 8.83 8.50 6.31 6.40 6.50 6.66 8.50 8.07 7.87 8.91 9.20 9.12 8.51
0.13 0.20 0.10 0.04
0.09 0.06 0.02
0.03 0.03 0.02 0.03 0.06
0.02 0.01 0.08 0.04
0.04 0.08 0.04 0.11 0.02 0.01 0.01 0.05 0.06 0.02 0.11 0.02 0.04 0.20 0.09
0.03 0.10 0.01 0.03 0.03 0.02
0.12 0.11 0.08 0.10
0.02 2.02
0.05
0.02 0.05
0.57 0.55 0.74
0.02 0.03 0.02 0.06 0.02 0.04
See footnote 1 and references listed in Table 1.
0.04 0.17 0.20 0.21 0.03 0.09 0.06 0.14 0.41 0.49 0.39 0.23 0.36 0.59 0.40 0.19 0.01 0.15 0.09 0.09 0.25 0.17 0.25 0.12 0.10 0.10 0.08 0.08 0.08 0.46 0.07
Exchange K Ca/2 Total 0.02 0.02 0.03 0.07 0.05 0.57 0.04 0.05 0.10 0.05 0.03 0.07 0.26 0.15 0.19 0.15 0.03 0.02 0.01 0.15 0.20 0.31 0.05 0.01 0.06 0.20 0.22 0.19 0.26 0.01 0.15 0.32
0.09 0.01 0.06 0.01 0.16 0.25
0.64 0.10 0.06 0.06 0.86 0.12 0.32 0.22 0.26 0.52 0.64 1.14 0.83 1.30 1.28 0.72 0.40 0.88 1.08 1.30 0.30 0.36 0.68 0.68 0.74 0.86 0.46 0.26 0.18 0.44 0.30 0.36 0.32 0.02 0.42 0.38
0.79 0.30 0.18 0.13 0.93 0.21 1.06 0.46 0,47 0.60 0.83 1.20 1.03 1.74 1.84 1.37 0.78 1.43 1.82 1.73 0.51 0.38 0.98 0.97 0.83 1.42 0.68 0.52 0.36 0.74 0.62 0.63 0.66 0.11 1.03 0.73
0.52 0.62 0.68 0.75 0.10 0.51
IV
Chargeunbalance VI Total
-1.76 -2.05 -2.78 -2.46 -2.22 -2.05 -0.97 -2.23 -1.76 -0.67 -1.63 -1.76 -1.39 -1.76 -1.86 -1.63 -2.19 -1.75 -2.11 -1.78 -1.53 -1.53 - 1.01 -1.51 -2.21 -0.78 -1.47 -2.10 -2.14 -0.32 -0.42 -0.33 -0.82 -0.91 -1.64 -1.37 -1.33 -2.01 -1.94 -1.61
+0.99 +1.75 +2.62 +2.34 +1.29 +1.88 -0.04 +1.78 +1.30 +0.10 +0.82 +0.56 +0.38 +0.01 +0.04 +0.28 +1.40 +0.33 +0.29 +0.06 +1.01 +1.16 +0.04 +0.55 +1.37 -0.64 +0.83 +1.58 +1.80 -0.41 -0.22 -0.28 +0.17 +0.80 +0.63 +0.65 +1.35 +1.41 +1.20 +1.10
-0.77 -0.30 -0.16 -0.12 -0.93 -0.17 -1.01 -0.45 -0.46 -0.57 -0.81 -1.20 -1.01 -1.75 -1.82 -1.35 -0.79 -1.42 -1.82 -1.72 -0.51 -0.37 -0.97 -0.96 -0.84 -1.42 -0.64 -0.52 -0.34 -0.73 -0.64 -0.61 -0.65 -0.11 -1.01 -0.72 +0.02 -0.60 -0.74 -0.51
394
Brigatti and Poppi
Q - M O D E multivariate analysis following the basic principles found in K l o v a n and Imbrie (1971) and Davis (1973). The purpose o f this analysis was to ascertain the similarities among several samples on the basis o f prefixed variables (chemical data in this study). At first, all variables were reduced to a percentage o f their range o f variability and so normalized. A n n.n correlation matrix (n = number o f samples) was created, and from this a prefixed number p (p < v) (where v is the number o f variables) o f eigenvalues and eigenvectors was extracted (principal factor score matrix). A p-dimensional space was so created where the coordinates o f the samples were obtained by multiplying the elements o f the eigenvectors matrix by the values o f the corresponding variables (principal factor loadings). Three p factors (F. 1, F.2, F.3) were rotated in p-dimensional space where the variance o f the sample loadings was maximized (varimax factor score matrix). The coordinates o f the samples in this new space were obtained as described above by multiplying the elements o f the varimax-factor score matrix by the values o f the corresponding variables. The sum o f the square o f these coordinates (communality) provided an index o f the reliability o f this set o f data to explain the variance o f the samples. To visualize the results, the coordinates so obtained were normalized and plotted in triangular diagrams whose apexes represent the three factors (F. 1, F.2, F.3). The computer program was used to distinguish different corrensite-type minerals from a chemical point o f view. In analysis (1), all proposed definitions (as in Table 1) were considered. In analysis (2), the samples were redefined as low-charge corrensite (C/Sap and C~ M) and high-charge corrensite (C/V and C/SC); the AIC/M was not considered. In analysis (3) all o f the samples (except AI-C/M) were compared to saponite and vermiculite (the chemical formulae o f saponite and vermiculite were derived from literature analyses reported by Brigatti (1982) and Brigatti and Poppi (1980) and recalculated as previously described for corrensite). In analysis (4) all o f the data in analysis (3) were compared to trioctahedral chlorites whose chemical formulae were also recalculated as corrensite from the chemical analyses in Foster (1962). In all analyses, data not sufficiently detailed (communality < 0.98) were not considered. The meaning o f t h e vertices (F. 1, F.2, F.3) in the triangular diagrams (Figure 1) can be deduced from the varimax factor score matrix relative to each one o f them (Table 4).
Clays and Clay Minerals
oo
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oddd
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RESULTS The correlation matrix between b-dimensions and chemical properties o f corrensite is given in Table 5. The b-dimension seems to correlate principally with the charge unbalance and the amount o f octahedral Mg, but the low variation o f the b-dimension and high
e~
m
e~
Vol. 32, No. 5, 1984
Crystal chemistry of corrensite
Analysis (1)
11
"Al-chloritelmontmoriilonite,, 9 chlerite/sap0nite o chlorite/montmorillonite--~ chl0rite/vermiculite 9
/\
/
/ ~n\ -- \
395
Analysis (3)
~1 /~
vermiculite+ corrensite-~ sap0nite--o
FA1
vermiculite+ corrensiteA
E3
E2
Analysis (2)
low charge: chlorite/montmorill0nite o chlorite/saponite-o
F~I
/\
/oo~
// / _D "
\
\
Analysis (4)
/
/ \
\
saponJte--o
high charge: cMor!te/swel!ing-chluri!e_o
\
E3 E2 ~ Q-MODE multivariate analysis of selected corrensites, chlorites, saponites, and vermiculites.
E2
Figure l.
v a r i a t i o n o f t h e c h e m i c a l c o m p o s i t i o n d i d n o t allow a reliable h y p o t h e s i s o n t h i s c o r r e l a t i o n to b e p u t forward. T h e results o f t h e Q - M O D E m u l t i v a r i a t e a n a l y s i s c a n b e s u m m a r i z e d as follows (Figure 1):
E3
Analysis (1). T h e
factors F. 1, F.2, F.3 are affected p r i n cipally b y o c t a h e d r a l p o p u l a t i o n s . T h e A 1 - C / M m a terials are distinct, b u t t h e i r c h l o r i t e c o m p o n e n t s are probably dioctahedral; the C/V materials plot towards t h e F. 1 apex; t h e C / S a p m a t e r i a l s are s c a t t e r e d a n d n o t
Table 5. Correlation matrix between the b dimension and chemical properties of selected corrensites. Variance
1
2
3
4
5
6
7
1 2 3 4 5 6 7
1.000
-0.786 1.000
0.627 -0.861 1.000
-0.565 0.798 -0.965 1.000
-0.782 0.984 -0.914 0.863 1.000
-0.296 0.394 -0.640 0.643 0.524 1.000
0.884 -0.769 0.584 -0.518 -0.770 - O. 149 1.000
1 = b (•); 2 = Mg(VI)/Z(VI); 3 = (A1 + Fe3+)(VI)/~(VI); 4 = (Mg + FeZ+)(VI)/Z(VI); 5 = Mg(VI); 6 = Si(IV)/AI(IV); 7 = Charge imbalance.
Brigatti and Poppi
396
Clays and Clay Minerals
/ \ AI Lwj
corrensite chlorite
9
vermiculite
o
saponite
~
L~
o
o
// 9149S~39
q%
o
o
[]
o
o o
Q
o
Hg [w]
(Fe3 + Fe2)Ew]
Figure 2. Relation between Mg(VI), AI(VI), (Fetot)(VI)in selected corrensites, chlorites, saponites, and vermiculites.
distinct from the C/M materials. Apparently F. 1 (principally affected by Mg in octahedral coordination) discriminates the C/V materials even if some C/Sap materials fall into the C/V area.
Analysis (2). A high Mg content in octahedral coordination seems to characterize high-charge corrensites, but some low-charge corrensites also plot in this area. Low-charge corrensites fall into a very large area compared with that of high-charge corrensite because of the larger compositional range of the low-charge materials.
Analysis (3). The vermiculites, saponites, and corrensites plot in three distinct areas. The broader compositional range of corrensites (in particular AI in the octahedral sheet) and the differentiation of the three
groups on the basis of their chemistry can be deduced from the diagram.
Analysis (4). O n the basis of F. 1 (principally affected by octahedral Mg content), saponite and vermiculite can be distinguished from chlorite and corrensite, whereas, F.2 (principally affected by Fe in the octahedral sheet) distinguishes corrensites from chlorites. Corrensite has a larger compositional area than chlorite. DISCUSSION A N D CONCLUSIONS The distinction between vermiculite and saponite has generally been made on the basis of layer charge that is clearly correlated with the composition of 2: l silicate layer. The experimental tests to determine the
Vol. 32, No. 5, 1984
Crystal chemistry of corrensite
layer charge of smectites are relatively standardized (Brindley and Brown, 1980), and thus chemical treatments to distinguish vermiculite from saponite are commonly used to characterize the swelling layer component of corrensite and, thus, to describe the corrensite itself. The compositional variability of corrensite is due to the compositional range of both the swelling and the nonswelling component; the chemical variability is higher in the chlorite layers than in the swelling layers. The data used to evaluate the swelling layer charge are, thus, not reliable for corrensites because of the large proportion of the chlorite component in the total composition. Compositional transitions between chlorite, corrensite, and trioctahedral smectites (such as saponite or vermiculite) are also evident. The continuous chemical variation of corrensite between trioctahedral chlorite and saponite or vermuculite can be hypothesized on the basis of Mg and Fe mobilization, probably due to hydrothermal solutions, as is shown in analysis (4) of Figure 1. In particular, Fe appears to play an important role in the chlorite-smectite transition, as is shown also in Figure 2. In this triangular diagram, saponite, vermiculite, corrensite, and chlorite are plotted in terms of their octahedral population (A1-Mg-Feto0. It can be seen that AI always constitutes less than 30% of the octahedral populations, whereas a continuous range between Fe and Mg is shown. Where Fe/(Fe + Mg) > 50%, only chlorite is present: with an increase in Mg, chlorite seems to transform into interlayer minerals (such as corrensite) and finally (probably because of iron oxidation, as is shown in analysis (4) of Figure 1) into trioctahedral smectites, such as saponite and vermiculite. The statistical analysis shows that although chemically corrensites can be distinguished from saponites, vermiculites, and chlorites, distinct compositional fields for the various types of mixed-layer chlorite/swelling layer minerals cannot be drawn. Thus, corrensite must be described chemically as a mineralogical species characterized by an interstratification ofa trioctahedral chloritic component and an ill-defined trioctahedral swelling component, as suggested by Bailey et al. (1982) from a structural point of view. ACKNOWLEDGMENTS The authors thank Professors J. J. Fripiat and F. Lippmann for their critical reading of the work and Prof. A. Alietti for valuable discussion. P. L. Hauff kindly made available her unpublished data on corrensite. Thanks are also due to Mr. W. Lugli for the illustrations. This investigation was made possible through the financial support of the Consiglio Nazionale delle Ricerche, Roma and of the Centro di Calcolo dell'UniversitY, Modena.
397 REFERENCES
Alietti, A. (1957a) Ilmineraleinterlaminatoclorite-saponite di Gotra (Valle del Taro, Appennino parmense): Attie Mem. Accad. Scienze Lett. Arti Modena 15, 1-14. Alietti, A. (1957b) Some interstratified clay minerals of the Taro Valley: Clay Min. Bull. 3, 207-211. Almon, W. R., Fullerton, L. B., and Davies, D. K. (1976) Pore space reduction in Cretaceous sandstones through chemical precipitation of clay minerals: J. Sed. Petr. 46, 89-96. April, R. H. (1980) Regularly interstratified chlorite/vermiculite in contact metamorphosed red beds, Newark Group, Connecticut Valley: Clays & Clay Minerals 28, 111. April, R. H. (1981) Trioctaheclral smectite and interstratifled chlorite smectite in Jurassic strata of the Connecticut Valley: Clays & Clay Minerals 29, 31-39. Bailey, S. W., Brindley, G. W., Kodarna, H., and Martin, R. T. (1982) Report of The Clay Minerals Society Nomenclature Committee for 1980-1981: Clays & Clay Minerals 30, 76-78. Blatter, C. L., Robertson, H. E., and Thompson, G.R. (1973) Regularly interstratified chlorite-dioctahedral smectite in dike intruded shales, Montana: Clays & Clay Minerals 21, 207-212. Bradley, W. F. and Weaver, C. E. (1956) A regularly interstratified chlorite-vermiculite clay mineral: Amer. Mineral. 41, 497-504. Brigatti, M. F. (1982) Hisingerite: a review of its crystal chemistry: in Proc. Int. Clay Conf., Bologna, Pavia, 1981, H. Van Olphen and F. Veniale, eds., Elsevier, Amsterdam, 97-110. Brigatti, M. F. and Poppi, L. (1980) Vermiculite and its relations to parent materials as revealed by chemical features: Miner. Petrogr. Acta 24, 123-134. Brigatti, M. F. and Poppi, L. (1984) "Corrensite like minerals" in the Taro and Ceno Valleys, Italy: Clay Miner. 19, 59-66. Brindiey, G. W. and Brown, G. (1980) Crystal Structures of Clay Minerals and Their X-ray Identification: Mineralogical Society, London, 495 pp. Churchman, G.J. (1980) Clay minerals formed from micas and chlorites in some New Zealand soils: Clay Miner. 15, 59-76. Davis, J. C. (1973) Statistics and Data Analysis in Geology: Wiley, New York, 550 pp. Earley, J. W., Brindley, G. W., McVeagh, W. J., and Vanden Heuvel, R. C. (1956) A regularly interstratified montmorillonite-chlorite: Amer. Mineral. 41, 258-267. Foster, M. D. (1962) Interpretation of the composition and a classification of the chlorites: U.S. Geol. Surv. Prof. Pap. 414A, 33 pp. Galan, E. and Doval, M. (1977) A proposition to name three regular interstratified minerals containingchlorite: in Proc. 3rd European Clay Conf., Oslo, 1977, I. Th. Rosenquist, ed., Nordic Soc. Clay Res., Oslo, Norway, 61-64. Gallitelli, P. (1956) Sulla presenza di un minerale a strati misti clorite-vermiculite ("swelling-chlorite") nei diabasi di Rossena e Campotrera nell'AppenninoEmiliano: Acc. Naz. Lincei Rend. 8, 146-154. GalliteUi, P. (1959) The mixed-layer minerals in the "Argille Scagliose" of the Allochtonous Formation of Northern Apennines(Italy): Congr. Gdol. lntern., Compt. Rend., 20th, Mexico City 1956, Comit~ Intern. Estudio Arcilas, 23-26. Kimbara, K. (1975) Regularly interstratified clay minerals of chlorite and saponite ("corrensite") in the Miocene Green TuffFormation in Japan: Bull. GeoL Surv. Japan 26, 669679.
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Kimbara, K. and Shimoda, S. (1972) An iron-rich saponite and a randomly interstratified mineral of chlorite and saponite in a pillow lava at Nibetsu, Aldta Prefecture. J. Clay Sci. Soc. Japan 12, 133-140. Klovan, J. E. and Imbrie, J. (1971) An algorithm and FORTRAN IV program for large scale Q-MODE factor analysis and calculation of factor score: J. Math. GeoL 3, 61-78. Lippmann, F. (1954) Uber einen Keuperton yon Zaisersweiher bei Maulbronn: Heidelberger Beitr. Mineral Petrogr. 4, 130-134. Lippmann, F. (1956) Clay minerals from the Rot member of the Triassic near G6ttingen, Germany: J. Sed. Petr. 26, 125-139. Lippmann, F. (1957) Die Tonminerale des GSttinger Rot: Fortsch. Miner. 35, 28-30. Lippmann, F. (1976) Corrensite, a swelling clay mineral, and its influence on floor heave in tunnels in the Keuper Formation: Bull. Int. Ass. Engin. GeoL 13, 65-70. Lippmann, F. and Johns, W . D . (1969) Regular interstratification in rhombohedral carbonates and layer silicates: Neues Jahrb. Min. Mh. 5, 212-221. Martin Vivaldi, J. L. and MacEwan, D~M. C. (1960) Corrensite and swelling chlorite: Clay Min. Bull. 4, 173-181. Mackenzie, R. C. (1972) Differential ThermalAnalysis: Academic Press, London, 775 pp. Melnik, U . M . (1959) Corrensite(vermiculite-chlorite)from the gabbro-diabases of Volhynia: Mineral Sb. L'vov 13, 387-395. Mongiorgi, R. and Morandi, N. (1970) Al-saponite e strati misti dorite/Al-saponite nelle idrotermaliti di una breccia a eontatto coi diabasi di Rossena nell'Appennino reggiano: Miner. Petrogr. Acta 16, 139-154. Nichols, C.R. (1970) Diabase argillation at King Mountain, Kiowa County, Oklahoma: J. Sed. Petrol 4, 848-854. Pacquet, A. (1968) Analcime et argiles diag6n6tiques dans
Clays and Clay Minerals
les formations s&limentaires de la r6gion d'Agades (R6public de Niger): M~m. Serv. Carte GdoL Als.-Lorr. 27, 221 PP. Peterson, M. N. A. (1961) Expandable-chloritic clay minerals from Upper Mississippian carbonate rocks o f the Cumberland Plateau in Tennessee: Amer. Mineral 46, 12451269. Seki, Y., Liou, J. G., Oki, Y., Dickson, F. W., Sakai, H., and Hirano, T. (1980) The interaction between Miocene volcanogenic rocks and seawater-meteoric water mixtures in near coast undersea part of the Seikan Tunnel, Japan: Mem. Hydrosci. Geotechn. Lab. Saitama Univ. 1, 1-114. Shimoda, S. (1970) An expandable chlorite-like mineral from the Hanaoka mine, Akita prefecture, Japan: Clay Min. Bull. 8, 352-359. Shirozu, H., Sakasegawa, T., Katsumoto, N., and Ozaki, M. (1975) Mg-clflorite and interstratified Mg-chlorite/saponire associated with Kuroko deposits: Clay Sci. 4, 305-321. Sudo, T. andKodama, H. (1957) Analuminianmixed-layer mineral of montmorillonite-chlorite: Z. Kristallogr. 109, 379-387. Sugiura, S. (1962) Chlorite-vermiculite mixed layer clay mineral from Noto mine, Ishikawa Prefecture: J. Miner. Soc. Japan 5, 311-323. Taguchi, S. and Watanabe, T. (1973) Clay minerals associated with gold ores from the fuke mine, Kagoshima Prefecture, with special reference to chlorite-saponite interstratified mineral: Sci. Rept., Kyushu Univ., GeoL 11, 243250. (Abstract, Min. Journ. 8, 211, 1976.) Takahashi, H. (1959) A regularly interstratified Mg-montmoriUonite-chlorite from the Tsumemi dolomite deposit, Fukuoka Prefecture, Japan: J. Miner. Soc. Japan 4, 151156.
(Received 5 March 1983; accepted 12 March 1984)
Pe31oMe--CTaTHCTHqeCKHeaHanH3bi YlHTepaTypHblXXHMHqeCKHX~aHH5IX 1Io KoppeH3HTOBbIMMnHepaJlOM BIaIrI~3bIBaIOT 6onbmyra KOMnOaHKHOHHyIOpa3Hoo6pa3HOCTb, KOTOpa~I6oJICC oqeBn~IHas OKTaa~pHqeCKO~l, qeM TeTpaaB1oi,iqecgofl KoopJIItHaIIHH.Mg 3altHMaeT 40--80% OKTaa~pHqeCtCHXMeeT, Tor~a KaK OCTa.rtl,HbIe MeCTaaanoJln~mTCa A1 n Fe 2§ Ilpn6nH3nTe~IbHO 15--30~ TeTpaa/IpHqeCKHXMeeT3anonHeHOAI. HeCMOTpg Ha rOMnOaHtmOHnympaaHoo6paaHocrb HeT oqesrI~IblX qeTKHXo6naereft ~ m Hecrom,Knx THnOSCMe/I/aHHOcnofmoro rpHOrTaa/tpHqeCKOrO xnoprtTa/TpHorraaapHqecxoro Ha6yxalomero cnofl. Cpa~HeHae c'raTneraqeCKHXaHanHaOa KOMHOaHUJtHKoppeHaUTaC CanOHHTOM,BepMIIKyJmTOMn XJIOp~ITOMH~OaHT Ha MbICnI,, qTO KoppeHaHT SBnaeTC~ npoMe~ryrOqHblMcOe~HHeHHeMM e ~ y TpHOKTaaApH'~eCKHMxnOpHTOM a rpHoKpaa~qaHqecrltM CMelCrHTOM.EC~IHFe/(Fe + Mg) > 50%, TOnbKOXJIOpnr ~ a ~ e r c ~ npe~HOqTHTe~i,HblM, ~OC yaemr~eHHeM Mg xZOpHT, no BHJIHMOMy, npeo6paaoa~,maeTc~ ~ xoppelt3HT ~ npn nocze~yiomeM ornc~ienHa ~eneaa--a TpHoicraa)xpHqecrnfi CMeKTHT.HeCMOTp~tHa XHMH~ecxoepa3~n~He MeeKly roppea3nTOM, X.rIOpHTOMH CaHOHHTOM,roppenanTbI, no BI~IIHMOMy,flBJIglOTCflXHMHqeCKHxopomo-onpe~eJ~eHHbIMHBH~aMH. C ~DyrO~ICTOpOHbI,KoppeH3HTbIHe MoryT 6bITb XHMHqeCI(HcxapaKTepH3oaaHbl Ha ocHoae HX Ha6yxammero KOMHOHeHTa.TaXHM o6pa3oM, COSpeMeHHOeonpege~eHHe xoppeHaHTa r a r peITJDIpHOI~I npocJIofirH 1:1 TpHOKTaa/IpHtleCKOFOXJIOpHTa H TpHOKTaa~pHqecKoro CMeKTHTa HJIli BepMHKyYIHTagBnseTcs COOTSCTCTayrOmHM. [E.G.] Resiimee--Statistische Analysen von chemischen Daten aus der Literatur fiber Corrensitminerale deuten aufeine grol3e Variabilifiit der Zusammensetzung hin, die in der oktaedrischen Koordination ausgepr~igter ist als in der tetraedrischen Koordination. Mg besetzt 40-80% der oktaedrischen Pl[itze, wS.hrend A1 und Fe den Rest besetzen. Ungef~ihr 15-30% der Tetraederpllttze werden yon A1 besetzt. Trotz dieser chemischen Variabilit~t sind keine getrennten Bereiche far die verschiedenen Arten yon Wechsellagerung aus trioktaedrischem Chlorit und trioktaedrischer quellflihiger Schicht zu erkennen. Statistische Analysen der Corrensitzusammensetzung im Vergleich zu Saponit, Vermiculit und Chlorit deuten darauf hin, dal3 der Corrensit ein Zwischenglied zwisehen trioktaedrischem Chlorit und trioktaedrischem Smektit ist. Wenn das Verhiiltnis Fe/(Fe + Mg) > 50% ist, wird Chlorit allein bevorzugt, aber mit zunehmendem Mg-Gehaltscheint Chlorit in Corrensit umgewandelt zu werden und dann durch Oxidation yon Fe in trioktaedrischen Smektit. Trotz der ehemisehen Variabilit~t zwischen Corrensit, Chlorit und Saponit scheint der Corrensit eine gut definierte Phase zu sein. Aufder anderen Seite kann der Corrensit chemisch nicht aufgrund seiner quellfiihigen Komponente charakterisiert werden. Daher ist die gegenw~trtige Defmition yon Corrensit als eine regelm~il3ige 1:1 Wechsellagerung yon trioktaedrischem Chlorit und entweder trioktaedrischem Smektit oder Vermiculit zutreffend. [U.W.]
Vol. 32, No. 5, 1984
Crystal chemistry o f corrensite
R~sume--Des analyses statistiques de donnees chimiques de la litterature concernant les mineraux corrensites suggerent une variabilite de composition tres grande, plus evidente darts la coordination octaedrale que tetraedrale. Mg occupe 40-80% des sites octaedraux, avec AI et Fe 2+ remplissant le reste. Approximativement 15-30% des sites tetraedraux sont remplis par AI. Malgre cette variabilit6 de composition, il n'y a pas d'apparence de champs distincts pour les diiferents types de couches melangees chlorite triocta&lrale/couche gonflante trioctaedrale. Des analyses statistiques de la composition de corrensite comparee a la saponite, la vermiculite et la chlorite suggerent que la corrensite est un intermediaire entre la chlorite trioctaedrale et la smectite trioctaedrale. Si Fe/(Fe + Mg) > 50%, la chlorite seule est favorisee, mals avec l'augmentation de Mg, la chlorite semble se transformer en corrensite et ensuite, par oxidation de fer, en smectite trioctaedrale. Malgr6 la variabilite chimique entre la corrensite, la chlorite et la saponite, la corrensite semble ~tre chimiquement une e s p ~ e bien definie. Mais d'autre part, la corrensite ne peut pas 6tre caracterisee chimiquement sur la base de son compost gonflant. Ainsi, la definition actuelle de la corrensite en tant qu'interstratification 1:1 de chlorite trioctaedrale et soit de la smectite ou de la vermiculite est appropriee. [D.J.]
399
