some from weathering
A smooth, black rock is likely to be basalt. Basalt is an extrusive igneous rock that is commonly dark in color and has a fine-grained texture, giving it a smooth appearance.
Yes, it is.
obsidian
Sure, a boulder is a large rock.
Pavement or smooth rock runoff affects waterways because they create more impervious surfaces.
Shale
It can be both
A rock is a option!
it can be rough or smooth
rough
smooth and rough
Metamorphic rock can be coarse grained or fine grained.