Monster, the rocks/crystal things in the second texture look just randomly scattered there, and I doubt that's the intended result.
As for the first one, it looks cool, I noticed a strong influence of Lava Reef in that. If you want to avoid it looking tiled, you can try making it as big as 256x256 and rather than resize it, add some depth. However it looks no less tiled than the LRZ textures already present.
My main criticism would be the coloring, which looks very flat. While blocky shading *is* something that works well for SRB2, its still good to have some light dark variation. Try using lighter or darker colors from the color range you used and see if you can make it look good with a little variation. A little added depth definitely wouldn't hurt.
My last gripe is that it doesn't *quite* look like something you'd see in a Desert, its more of a Hidden Palace texture. Right off the bat those look more like crystals than rock.
And GemEB, the current textures have been exhausted to the point where its hard to come up with an original stage design without making new ones, which nobody ever does here. (haven't seen ANY recently other than Palmtree Panic excluding secrets) Furthermore having its own texture set will make ACZ its own theme, rather than becoming a mixture of other suitable themes. I'm hoping that every official SRB2 level will have its own exclusive texture set, and that RVZ is going to lose the repetitive MMZ textures it has in the demo.