i recognize two issues with your tiles right now.
One is, and that applies to all your art i've seen so far: your ramps are very linear, you barely shift the hues. you could try to be more bolt with it, just crank the slider up and down and see the effect, and also pay close attention to the color modifications in the numerous edits, like i mentioned in the other thread, a shadow is not just darker.
Secondly i am not sure if this is supposed to be dirt or rock. The colors suggest a dirt like surface, while the shapes seem more rock-inspired (although they honestly look like teeth to me, which is kind of creepy
)
It's been a while since i've been doing some rocky business but i gave it a shot anyways:
A couple month ago i started
a thread about rocks on here, lots of topics were touched and i learned a lot from it, maybe you can take something away from it as well.
It touches the topic of colors, hue changes, lighting, ambience and then some.