Not sure they did, though perhaps later on after the industrial revolution. Early English coal for glassmaking, notably including Ravenscroft inventing lead cry

Not sure they did, though perhaps later on after the industrial revolution. Early English coal for glassmaking, notably including Ravenscroft inventing lead crystal a little later in the century used sea coal: Coal with unique properties that washed up on beaches, mainly in the NE of England and East coast of Scotland. It had several other uses. Ships would transport it south daily. It burned far hotter than most regular mined coal, and was quite bituminous with very little ash. Not quite sure when it was first adopted as they discovered it burned hotter, though it was definitely part of the step forward of bottle production. Not sure when it was crowded out by other coals, as sea coal was relatively limited quantity, either. (Note there were one or two NE English inland seams of sea coal, with the unique properties, so descriptions can sometimes seem confusing). Some photos of the industry's last death throes (apologies for DM link, but as always they include lots of pics): https://www.dailymail.co.uk/news/article-2309040/The-twilight-seacoaling-Pictures-capture-dying-industry-men-scrape-coal-washed-sea.html https://www.dailymail.co.uk/news/article-2309040/The-twiligh... Edit: BBC page and prog referencing its use in bottles (sea coal turns up surprisingly few references, and Wikipedia describes it incorrectly): https://www.bbc.co.uk/programmes/articles/RG2DjvRx861cLSWtwccvjY/10-wondrous-facts-about-the-wine-glass https://www.bbc.co.uk/programmes/articles/RG2DjvRx861cLSWtwc...