Structures crystalline vermiculite

FIGURE 1.1 Schematic illustration of the structure of a crystalline vermiculite. Within the clay plates, the open circles represent oxygen, the closed circles silicon, and the shaded circles magnesium. The oxygen-oxygen separation of the surface layers is about 7 A. In the interlayer region, the open circles represent water molecules and the shaded circles univalent cations. The dotted lines show the unit cell. 

Properties Platelet-type crystalline structure. High porosity, high void volume to surface area ratio, low density, large range of particle size. Insoluble in water and organic solvents soluble in hot concentrated sulfuric acid. Water vapor adsorption capacity of expanded vermiculite less than 1%, liquid adsorption dependent on conditions and particle size, ranges 200-500%. Noncombustible. 

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