Structures can exist or not, another characteristic of a surface is how hard or soft it is, and this is a 3rd axis: how rough or smooth a surface is. These words are new ones so please check the new Incomplete Rejistanian Dictionary and update possible offline-copies of it.
What exactly is the difference between hamik and sandat you ask? Good question: hamik does not mean that the structure is necessarily very prominent and comparisons and adverbs like al would refer to a gradient in regularity. The wood of my bookshelf has a smooth surface but it is has the structure of the wood and thus hamiks.
Also sounds can be sandat if they are just something you cannot stand. Fingernails on blackboard is a good example. It does not have to be a loud sound, just one, which is incredibly annoying. Roads full of potholes or unasphalted ones also can be described using this term.
Example: Yjik’het’ny salankij min’sandat al. (road mountain 3pl-be_rough very. Mountain roads are very uneven) listen