Sea coal

Well, sometimes you just have to have to ask.  I have periodically over my life seen reference to sea coal, more commonly when reading in an English context than American.  I see it often enough to recognize the term but not so frequently that its precise definition has ever had any usefulness.

I had sort of always vaguely assumed that somehow it was simply referring to coal transported by coastal colliers.  But as I say, I never gave it much thought.  

Till I checked it just now.

sea coal

/sē kōl/

noun

ARCHAIC

mineral coal, as distinct from other types of coal such as charcoal.

Basically geologically mined anthracite or lignite versus manufactured charcoal.

OK.  I don't that knowing this will ever make a difference but life is fulled of unexpected eventualities.