clinker

She left the road at the little shed where he whom she still regarded as her father used to keep his tricycle, and walked up the clinker path towards the house.

The coal was terrible stuff—Indian, Abdul told me. The "dart" was used often and I saw some monster clinkers.

This wall of rock, which had no doubt once formed the lip of the crater, was about a mile and a half thick, and still covered with clinker.