@michalis: I didn’t want to simplify stone problematic just to a cube 
Stones are very mysterious objects.
But as you said -stones are abstract. There are many kinds of stone material and thousands visual results after ages of different weatherforecasts. That is why I tried to use a bit randomness from generated shards or use physics to get more natural looking.
For more accurate result (and for artists needs) user refinement is needed of course.
I open this thread because it looks like effective start to me - If you compare this result (that takes 5 minutes) with modeling from the box, you can’t say no 
If yo have massive scene or car riding next to the valley . . . looks like useful way.
Mesh keeps his very elementary topology, and all is done via few modifiers, so you can go to an edit mode and with “L” select specific shard and change composition, make a hole, change displace value to reshape from corpulent to sharp edge kind, or what ever.