ifu y'ibumba ya bentonite ni minerval idafite ubutare hamwe na montmorillonite nkibigize imyunyu ngugu. Imiterere ya montmorillonite ni ubwoko bwa 2: 1 bwa kirisiti igizwe na tetrahedrons ebyiri ya silicon-ogisijeni hamwe na octahedrons ya aluminium-ogisijeni. Hano hari cations zimwe murwego rwubatswe, nka Cu, Mg, Na, K, nibindi, kandi imikoranire yiyi cations na selile ya montmorillonite ntigihungabana cyane, kandi biroroshye guhanahana nizindi cations, bityo rero ifite ion nziza. Ibihugu by’amahanga byakoreshejwe mu mashami arenga 100 mu bice 24 by’inganda n’ubuhinzi, kandi hari ibicuruzwa birenga 300, bityo abantu bakabyita “ubutaka rusange.”