Bentonite's main mineral, montmorillonite, absorbs water between its layers, swells, and binds into solid clumps around urine, with sodium grades swelling best.
The fine granules resemble the sandy soil cats' ancestors used, giving high acceptance, which is why behavior-problem cats are often switched back to bentonite.
When buying, judge clumping speed and clump strength: slow clumping seeps and sticks to the pan, while fragile clumps crumble and contaminate the box; a water test compares brands.
Trade-offs are weight, relatively higher dust, and non-biodegradability, so weigh them for sensitive airways; mix gradually when switching to check acceptance.
