I saw a thread on the container gardening thread ( I think...) where Justaguy did an experiment with cat litter. I think his test showed that the cat litter would almost turn to mud, once saturated with water for a long time. You could probably do a search on cat/kitty litter, and pull it up.

EG

also the kitty litter breaks down because it is clay, i read that in the compost forum (i believe) and the vermiculite does not. someone was trying to dispute it, or something like that, actually it might have been here!! LOL ~Medo

Here is a link that might be useful: Barehanded Totally Nutso Gardener!! **Big Grinn**

Most kitty litters are just clay, so it's not going to serve the same function as the vermiculite at all. Sorry.