Always looking for alternatives, I found this when I did an internet search on TruGro (the expanded shale we've been hearing about). It's from that dirt doctor's website:

"Q. What do you think of the product called TruGro that had the ad above your column last week? Is it really better than the natural soil amendments that you have been promoting? Â M.G., Dallas

A. TruGro is a basically inert material that is a by-product of TXI concrete manufacturing. It is marketed as a product to aerate the soil and hold water. It costs more than lava sand which works better in all ways. For the price, any of the following amendments would be superior: lava sand, basalt, zeolite, Texas greensand, decomposed granite and compost."

I'm wondering what some of you think of these other materials he mentioned as being better than the expanded shale/TruGro (eg. lava sand, basalt). And if you like any of them, are they easy to find for purchase (I am in Chicago). Can I just use some good soil, some of the coir (instead of peat moss) and a good variety of compost if I can't find vermiculite or TruGro or any of these other things?