Bentonite Mineralogy Part 1: Methods of Investigation - Posiva

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Table 3-2. Reported values of relative intensifies, given by equal amounts of minerals (Olsson, 1991). 14 Author/miner. Pia g. K-fs Quartz Afb Chlorite Illite Verm. mount peak 3,19A 3,25A 3,34A 4,26A 8,3A 7A t4A lOA t4A Schultz ( 1964) 1 1 2 R Snall et al. (1979) 1 1 3 1 6 2 4 0 Backman et al. (1986) 3 1 2 R Islam&Lotse (1986) 0,5 0,5 0,5 2,2 1 2,5 0 Pederstad& Jorgensen (1985) b b b 2 1 3 0 Roaldset (1978) 3 1 1 1 2 1 0 Jorgensen (1965) 1 0,3 0,3 1 0 Melkerud (1983) 1 0,8 0,3 1 6 2 4 O+R Olsson (1991) 1,3 1 0,6 0,8 0 Legend: Plag., plagioclase; K-fs, potassium feldspar; Afb, amphibole; Verm., vermiculite; mount, XRD mount, random (R) or oriented (0). b, the authors used equations: wK-Js/Wq = 0,97 x IK-Js/Iq- 0,04; Wp/wq = 0, 79 x Ip/Iq-0,07. An example: A mixture ofplagioclase, K-feldspar and quartz, peak intensity of each is 100 (quartz 4,26A peak). According to Islam and Lotse the mixture contains 33,3% of each mineral, according to Roaldset and Jorgensen 14,3% plagioclase, 42,9% Kfeldspar and 42,9% quartz, according to Melkerud 17,9% plagioclase, 22,4% K-feldspar and 59,7% quartz and according to Olsson 22,4% plagioclase, 29,1% K-feldspar and 48,5% quartz. At the Research laboratory of the Geological Survey of Finland, factors used for evaluation of mineral composition were calculated from patterns of mineral pairs with known proportions of each mineral (Table 3-3). Software determined the base line and the peak heights that were used for calculation of the factors. In most cases, quartz was one of the minerals and the intensity of its 4,26 A peak was taken as 1. The smectite used was montmorillonite from Wyoming. Using the factors from table 3-3, following percentages are received for the sample above: either 27,3% plagioclase, 27,8% Kfeldspar and 44,8% quartz or 37,2% plagioclase, 24% K-feldspar and 38,8% quartz, depending on the composition of plagioclase.
15 Table 3-3. The factors used for semiquantitative calculations of mineral composition at the Research laboratory of the Geological Survey of Finland Mineral Peak, d (A) Factor quartz 4,26 1 quartz 3,34 0,21 K-feldspar 3,25 0,62 Na-plagioclase 3,2 0,61 Ca-Na-plagioclase 3,2 0,96 biotite 10 0,16 muscovite 10 0,5 illite 10 0,5 vermiculite 14 0,28 chlorite 7 0,28 hornblende 8,45 0,46 kaolinite 7 4,3 smectite 14 2,46 calcite 3,03 0,2 dolomite 2,89 0,22 Kirsimae et al. (1999) used following factors: chlorite 14 A- 1,1; mixed-layer illitesmectite 10- 14 A- 1, illite 10 A- 2, kaolinite 7 A- 1; quartz 4,26 A- 4; K-feldspar 3,94 A- 16; hematite/pyrite 2,7 A- 3. Curve-fitting program was used to resolve peaks of poorly crystalline illite and illite/smectite mixed-layer mineral as well as those of well crystalline illite and chlorite. An inter-laboratory comparison was done by analysing two samples in 19 laboratories, mainly in Germany and Austria (Ottner et al., 2000). The semiquantitative evaluations were mainly done by XRD. The participants used different methods of pre-treatment, preparation, analysis and evaluation. The samples were a carbonate-bearing, smectiterich clay and a carbonate-free Quaternary loam that contains vermiculite and mixedlayer minerals. Reasonable conformity in quantitative results was obtained for the associated minerals (quartz, calcite, dolomite). Even qualitative identification of the clay minerals showed considerable divergences, causing a stronger deviation of quantitative data. Evaluated quartz content of the smectite-rich sample ranged from 11 to 67%, most of the values were between 20 and 29%, the evaluated smectite content ranged from 7 to 23,8% and mica content from 11,9 to 26%. Similar ranges were found in another inter-laboratory comparison. Three artificial mixtures of quartz, K-feldspar, plagioclase, calcite, dolomite, siderite, pyrite, kaolinite, 2:1 Al clay, 2:1 Fe clay and Fe-chlorite were sent to five laboratories for mineralogical analysis (Srodon et al., 2001). Quartz content was systematically overestimated (actual: 25% - estimation: 32-68%; actual: 30% - estimation: 34-63%); K-feldspar content was underestimated (actual: 5% - estimation: 0-3%; actual: 10% - estimation: 1-8%),
Page 1: POSIVA OY Working Report 2004-02 Be
Page 4 and 5: ABSTRACT In the first part of the r
Page 6 and 7: TABLE OF CONTENTS ABSTRACT TIIVISTE
Page 8 and 9: PART 1. METHODS OF INVESTIGATION- A
Page 12: 8 Mixed-layer clay minerals: Layers
Page 17: 13 4) Is the sample thick enough an
Page 22: Recommendation: 18 It is recommende
Page 27 and 28: - 4 SUMMARY ON RECOMMENDABLE METHOD
Page 29 and 30: PART 2. MINERALOGICAL RESEARCH OF S
Page 31 and 32: 20mm Figure S-3. Kutch bentonite, s
Page 33 and 34: 6 ANALYTICAL METHODS 29 Summary of
Page 35 and 36: 31 Table 6-2. Instrumental detectio
Page 37 and 38: 6.1.5 Coarse fraction 33 In connect
Page 42 and 43: Table 7-1. Minerals in addition to
Page 47: 43 The Friedland sample contains no
Page 54: 50 Figure 7-15. TEM-p holograph of
Page 58 and 59: Table 7-7. Contents of major elemen
Page 61 and 62: Table 7-9. Continued. 57 Sample La
Page 63 and 64: 59 charge. Therefore, more exchange
Page 65 and 66: 61 for the four Kutch samples studi
Page 67 and 68: 63 The Milos bentonites contain poo
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8 SUMMARY 65 The purpose of this st
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67 to Henning (1971), the position
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70 in the interlayer positions. The
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REFERENCES 73 Backman, C.-M., Bruse
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75 Inoue, A., Kohyama, N., Kitagawa
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77 Pusch, R., 1999. Is montmorillon
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PHOTOGRAPHS OF BENTONITE AND CLAY S
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20mm 81 20mm APPENDIX 1 (3/5) Milos
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20mm 83 APPENDIX 1 (5/5) 20mm Dnesi
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counts/s 5000 26.0 18.0 14.0 11 .0
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counts/s 2000 26.0 18.0 14.0 96 Str
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102 TEM PHOTOGRAPHS OF BENTONITES S
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Sample: Milos high grade 104 APPEND
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Bentonite Mineralogy Part 1: Methods of Investigation - Posiva

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