I've used laterite/lateritic soils in place of most substrates that needs coco fiber/except for my FBTs for years. In leopard geckos, snakes, hermit crabs and even fishes. I may have asked here once last year if laterites were safe for frogs knowing the iron content and frogs having semi-permeable skin. They are however hard to find in the US/UK/EU for some reason (geographic availability i guess) and as a result may be a bit costly.