Whinstone is a term used in the quarrying industry to describe any hard dark-coloured rock. Examples include the igneous rocks basalt and dolerite as well as the sedimentary rock chert.[1] [2]
Massive outcrops of whinstone occur include the Pentland Hills, and the Whin Sills.
The name 'whin' derives from the sound it makes when struck with a hammer. It is used for road chippings and dry stone walls, but its natural angular shapes do not fit together well and are not easy to build with, and its hardness makes it a difficult material to work.