Well, Turface is fired montmorillonite clay, and it is very popular among growers.
I buy Turface from a Turf Supply center, and it costs me 12$ for a 50 pound bag.
I screen the Turface with insect screen to remove the particles under 1/16 of an inch.

Turface does snap-crackle-pop when watered, but that's part of the fun! ;-)

Josh

Hmmmm... does it have a vaguely turpentine smell to it afterwards?

Oh well, I decided to test it out first. I pulled up a weed sapling tree out of the yard and put it in a container with nothing but this stuff. I figure if it doesn't die within a week or two it must be safe enough.

Hasn't been a full week yet, but I decided to call it early.

The sapling I was testing not only stayed green and healthy, it put on new growth while in the oil absorbent. Water retention in the clay was excellent, the natural clumping action made it nice and stable for the roots, it was all around excellent soil.

Only thing I don't know is how it reacts to freezing (I don't plan on finding out either, I'm growing a pepper bonsai in it, it will never be allowed to freeze), and I don't know if it will turn into mush a year from now.

But, with how cheap this stuff is (was like $6 for a 20-30 pound bag), and considering you need to prune roots every so often anyway, I'd say it wouldn't be a concern if it did break down after a year or so, since you'd be tending to the roots anyway and could just change it out while you're in there.

I definitely plan on using this stuff.

Although you can use 100 percent Turface (montmorillonite clay) to grow plants, you might find that it is too water retentive. I have been using a mix of half peat moss and half Turface to sprout clivia seeds (which are very slow to sprout but must be kept damp, and thus are prone to fungus attacks), and it is working very well. But I would never use pure Turface for mature plants. I prefer the classic gritty mix with equal parts of fir bark, granite grit and Turface for most house plants.

There is an interesting discussion of using 100 percent Turface on Gardenweb that I'll link to below.

Here is a link that might be useful: Question for tapla -- 100% Turface mixtures