seacoal

• sea coal
• sea-coal

From sea +‎ coal.

seacoal (uncountable)

English Wikipedia has an article on:

coal

Wikipedia

1. coal from inside the sea: mineral coal that washes up from the sea onto beaches, from which it can be collected and sold.
   • 1896, Martha Bockée Flint (1841-1900), Early Long Island, a colonial study‎^[1], Liveright, page 22:

     October 9, 1677. "John Thompson of Setauket has a permit to go to Flushing and other parts of Long Island to search for sea-coal, of which he hath probable information."

2. (historical, chiefly Southern England) coal from across the sea: mineral coal, as opposed to charcoal, in a time and place in which the former arrived by ship and the latter arrived overland (such as London in Elizabethan times).
   • 1662, Henry More, An Antidote Against Atheism, Book II, A Collection of Several Philosophical Writings of Dr. Henry More, p. 49:

     " […] and then of Sea-Coal and other necessary Fewel, fit for the working or melting of these Metalls; […] "

   • 2020, Ruth Goodman, The Domestic Revolution: How the Introduction of Coal Into Victorian Homes Changed Everything, Liveright, →ISBN, page xvii:

     And the change came fast. In 1570 there was still little sign of any major divergence from the traditional use of wood as fuel. Less than forty years later, in 1607, a case brought by the Crown in the Star Chamber stated as fact that ‘sea coal’ — a name for the coal that arrived in London by ship from Newcastle — was ‘the ordinary and usual fuel … almost everywhere in every man's house’. A single generation had made the switch.

3. (historical, technical, chiefly US) coal to be used at sea: a certain class of mineral coal, especially suitable for the steam engines of ships at sea and locomotives.

   Synonym: steam coal

   1. Such coal used in foundry practice, intermixed with foundry sand or applied in a layer on its face, to modify the behavior of the molten metal.