Light weight black shiny rock

[Photon]

Does anyone know what this rock maybe? Found it in a volcanic magma sill but it’s too light to be obsedian. It doesn’t fit the diabase rocks that are there. Not sure if it’s coal as it doesn’t leave a black soot.

 

[smokeythecat]

It's probably a coal clinker, waste from coal use in the past. We get them here a lot.

 

[flinthunter]

It's a possibility it could be scoria. Someone here with more knowledge of volcanic stone than me will probably know.