Mineralogy bentonites

Montmorillonite clays absorb water readily, swell greatly and confer highly plastic properties to a soil. Thus soil stress (Section 14.8) occurs most frequently in these soils and less commonly in predominantly kaolinitic types. Similarly, a soil high in bentonite will show more aggressive corrosion than a soil with a comparable percentage of kaolinite. A chalky soil usually shows low corrosion rates. Clay mineralogy and the relation of clays to corrosion deserves attention from corrosion engineers. Many important relationships are not fully understood and there is need for extensive research in this area. 

For compacted, low-permeability soil liners, the U.S. EPA draft guidance recommends natural soil materials, such as clays and silts. However, soils amended or blended with different additives (e.g., lime, cement, bentonite clays, and borrow clays) may also meet the current selection criteria of low hydraulic conductivity, or permeability, and sufficient thickness to prevent hazardous constituent migration out of the landfill unit. Therefore, U.S. EPA does not exclude compacted soil liners that contain these amendments. Additional factors affecting the design and construction of CCLs include plasticity index (PI), Atterburg limits, grain sizes, clay mineralogy, and attenuation properties. 

WEAVER (C.E.), 1956. Mineralogy of the middle Devonian Tioga K-bentonite. Amer. Min. 41, 359-62. 

Proc. Natl. Conf. Clays Clay Miner., 6th - Nall. Acad. Sci.Natl. Res. Counc., 1957 327-341. Bystrom, A.M., 1956. Mineralogy of the Ordovician bentonite beds at Kinnekullc, Sweden. Sver. Geol. Undersokn. Arsbok., 48 1-62. 

Reinink-Smith, L., 1982, The Mineralogy, Geochemistry and Origin of Bentonite Partings in the Eocene Skookumchuck Formation, Centralia Mine, S.W. Washington. Unpublished M.S. Thesis, W. Washington Univ., 1/9 pp. 

Peculiar geochemical (fig. 2) and mineralogical data (fig. 3) were obtained from the bentonite in the close proximity (20 - 30 cm) of the dike. 

The clay tested in the present work comes from deposits located in the north of Morocco (Nador area). The results corresponding to its textural and mineralogical composition have been published (Harti et al, 2007). The clay was found to be a mixture of phases, namely, opal, montmorillonite, kaohnite, muscovite, topaz, rutile, calcite, dolomite, suggesting a bentonite type clay. Textural studies perfomed with N2 adsorption desorption at 77 K have shown a BET sp>ecific surface area of 79 m g-i, and a negligible micropore volume of 0.002 cm g-i as comp>ared with total pore volume of 0.205 cm g-i. The pore size distribution obtained following BJH method revealed the presence of a wide pore size distribution in the mesopore range with a significant contribution of pores widths between 8 and 50 nm. 

Heimann, R.B. and Hooton, R.D. (1986) Mineralogical changes of various cement formulations during reaction with groundwater in the presence of Ca- and Na-bentonite at 150°C. Can. Mineral, 24, 289-302. 

Table 2 Mineralogical composition and properties of a Wyoming bentonite (MX-80 from Bentonite International, Duisburg Meiderich) und Montigel (Sud-Chemie, Bavaria) [124, 125]...

Guven, N. 1978. Bentonites Geology, Mineralogy, Properties and Uses. Developments in Sedimentary Series (24). Elsevier, Oxford. 

Smectites are water swellable clays that have a platy structure. Smectite is the mineralogical term for a group of clays, which includes montmorillonite, hectorite, and saponite. Most smectites are more commonly known under the geological term bentonite. By convention, bentonite is understood to be an ore or product with a substantial smectite content. The range of possible chemical variations in the basic smectite trilayer lattice starts with montmorillonite, the high-aluminum end member. Montmorillonite is composed of a central alumina octahedral layer sandwiched between tetrahedral silica layers. This is identical to the dioctahedral pyrophyllite structure except for small... 

Mineralogy of the Ordovician bentonite beds at Kinnekulle, Sweden. Sveriges Geol. 

Dahl, H. M., 1965. Clay mineralogy of some Permian bentonites from the Delaware basin area, Texas. Am. Mineral 50 1637-1646. 

Jorgensen, Per, 1964. Mineralogical composition of 2 Silurian bentonite beds from Sundvollen, S Norway. Norsk Geol, Tids, 44 227. 

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