Bentonite ni ibumba rya aluminium phyllosilicate ibumba rigizwe ahanini na montmorillonite. Ubwoko butandukanye bwa bentonite buriwese yitiriwe ikintu cyiganje, nka potasiyumu (K), sodium (Na), calcium (Ca), na aluminium (Al). Isosiyete yacu itanga cyane cyane sodium bentonite.