The Montmorillonite Group

This Na, being outside the lattice, can exchange with other cations (see cation exchange). Note that the part of the lattice in square brackets carries 0.33 units of negative charge, balanced by 0.33 units of positive charge, or Nao.33. (If we wish to avoid talking 

Like crystals of the kaolin group, a crystal of montmorillonite is many units thick, yet clearly the unit layers cannot be bonded chemically neither, indeed, can there be any hydroxyl bonding, since all the planar atoms on both sides of the units are oxygens. The unit layers are in fact held together by very weak residual forces, known as van der Waals forces, which are caused by slight Table 2 Empirical Formulae of some Montmorillonites 

---

Studies have been made of the fate of 3-amino 1,2,4 triazole herbicide in soils [106], while adsorption of aminotriazole by clay minerals has been postulated, little is known of the interaction with pure clay minerals, particularly of the montmorillonite group. The importance of such reactions cannot be overemphasized in view of their bearing on the persistence of the herbicide in the soil. 

ROSS (C.S.), HENDRICKS (S.B.), 1945. Minerals of the montmorillonite group. U.S. Geol. Surv. Prof. Papers 205. 

The first measurement of clay acidity was reported by Walling (72), who found that an acid-washed bentonite clay of the montmorillonite group imparted the acid color to p-nitrobenzene-azo(p -nitro) diphenyla-mine, which has a pKa of 0.43. At least part of this acidity, however, was thought to result from residual acid from the acid wash. 

Hofmann, U., Weiss, G.K., Mehler, A. and Scholz, A., 1956. Intracrystalline swelling, cation exchange, and anion exchange of minerals of the montmorillonite group and of kaolinite. Proc. Natl. Conf. Clays Clay Miner. 4th - Natl. Acad. Sci. Natl. Res. Counc., Pubi, 456 273-287. 

Ross, C.S., 1946. Sauconite - a clay mineral of the montmorillonite group. Am. Mineralogist, 31 411-424. 

Ross, C.S., 1960. Review of the relations in the montmorillonite group of clay minerals. Clays Clay Miner. Proc. 7th Conf., pp. 225-229. 

Sedletsky, I.D., 1937. Genesis of minerals from soil colloids of the montmorillonite group. Compt. Rend. Acad. Sci. U.S.S.R., 17 375-377. 

Magnesium aluminum silicate is obtained from silicate ores of the montmorillonite group, which show high magnesium content. The ore is blended with water to form a slurry to remove impurities and separate out the colloidal fraction. The refined colloidal dispersion is drum-dried to form a small flake, which is then micro-atomized to form various powder grades. 

HectOrite, Strese Hofmann s hectorite. Swelling and gelling clay of the montmorillonite group. Approx formula Na4Jp(Mg,Li)4Si(024(0H,F)4. Some analyses show neither 1-i nor F, whether by Oversight or by variation in the mineral is uncertain M. H. Hey, Mineral Species and Varieties (Brit. Museum, London, 2nd ed., 1962) p 205. 

These minerals are hydrated aluminosilicates which are characterized by a sheetlike structure and can be conveniently divided into three groups (1) the kaolinite group, (2) the mont-morillonite group, and (3) the potash clay (or hydrous mica) group (Table 7.7). In the kaolinite group, all have the same chemical composition and differ only in individual crystal structures. The montmorillonite group can be represented by means of ion substitutions in the general chemical formula. For example, in montmorillonite itself, approximately 16% of the aluminum... 

The perspective ones are the bentonite breeds of clays which include at least 70% of the minerals from the montmorillonite group. 

Beidellite. A clay mineral first found at Beidell, Colorado, USA it is an Al-rich member of the montmorillonite group. Belfast Sink. A domestic or industrial sink with an overflow and with its top edge plain cf. Edinburgh sink and LONDON sink. 

The montmorillonite group, also known as bentonite, comprises a number of clay minerals with dioctahedral (gibbsite) and trioctahedral (Si205) groups in three layer structures. They... 

---