Cobblestone variants created from exposed parameters within the Substance Designer graph, to generate mud and dirt.
Substance designer demo of the exposed parameters: An on/off toggle for moss or dirt, and a slider to control the level of growth from either one.
Testing the material in Unreal Engine 5. The exposed parameters within the substance .sbsar file carried over and made the generation of mossy or muddy variants quite easy.
Substance Designer material and references used.
This type of cobblestone is cast from iron slag, which tends to turn blue after some time. They are popularly found in Puerto Rico's capital, around the colonial area of Old San Juan.
I made these adoquines in Substance Designer, and blended them with my previously made forest moss material, seen here:
https://www.artstation.com/artwork/n0QBYX