I was at the Hydroponics shop getting some net pots for my soon-to arrive HL Nepenthes and I found this new product they are carrying called simply "Rocks"
25 dry liters for $14.99
The bag says it's inert shale that has been heated to 2200*F until it expands and shatters. I've wanted something larger than APS/Turface but not as large as Hydroton balls and this is just about right with 1/4 - 1/2" pieces. I will probably get a 3/8" metal screen to use as a sieve and separate the finer from larger bits but I was curious if any of you media mavens have played with this stuff yet?