Mmmmm, I like this stuff.
I finally got around to trying it out and it's fun. I rusted and ground the Iron for the iron oxide and hand ground the Aluminium powder via a file. Took ages but it's all nice and fine. Took 3 party sprinklers crushed on top of the thermite and three poked into the mix to get it started but it went quite nicely. I set it off in a hole about 2/3rds a foot deep and about an inch in diameter. I got a nice flame about the height of the hole high. went for a good 30 seconds. I used 30gm of FeO to about 15-20gm of the Al powder.
I dug the resulting metal core out of the ground and I'm gonna clean it up a bit to see how it went.