I have build a simple node group,with that i can control the Fresnel falloff curve (if a Material is rough then its reflection at grazing angels is more diffuse)
And additional to this i made a simple reflection grating control,(to control the reflection amout at the edges)
Then i had the idea to layering two PBR texture setups, with a costum node, that includes a gradient with with a noise texture to break up the fac.
this is a testrender with the two Materials with the costum node group used.
with more common Materials,leafs and brownish sand on comberstone.
snow on comberstone