Chuck,
I think for your type of hunting on lava rock the Australian leather will work best; however, they may wear out pretty fast. I ended up buying a bunch of tanned deer skin and making my own. It is not hard and they are cheaper, as well they can be sewn on a regular sewing machine. I have never used the Australin boots but the design I used is similar. I do provide a couple of holes for toe nails.
I would probably try the Cordura if I was still hunting in Texas. Here in TN briars and mud are my challenge.
Jim
