Bentonite EC No. 215-108-5, CAS No. 1302-78-9

Bentonite is the commercial name of a whole range of natural clays with a high water absorption capacity causing it to expand and swell. Bentonite predominantly consists of montmorillonite: a clay mineral belonging to a class of phyllosilicates called smectites. Bentonites may contain a variety of accessory minerals in addition to montmorillonite. These may include lesser amounts of other clay minerals such as kaolin, mica, illite, as well as non-clay minerals like quartz, feldspar, calcite, and gypsum. Bentonite quality, and, consequently, its applications, depend on whether it contains any of these other minerals.
Its density when dry varies depending on the quality, and may range from 2.2 to 2.8 g/cm3. Bentonite apparent density, when quarried and piled under natural moisture conditions, ranges from 1.5 to 1.8 g/cm3. The apparent density of milled bentonite products varies depending on mill fineness, ranging from 0.7 to 0.9 g/cm3.