The History of Slate…
Although some may think of slate as the forgotten stone, it produced more value in U.S. production than marble in 2015, the last year for which numbers are available. In 2015, slate production in the United States topped $19 million while marble production was valued at $17 million. While that is far less than the annual revenue produced in granite and limestone, it is shared mainly by less than 30 quarries in and near Southwestern Vermont. Slate traces its origins back to the mountains.
Millions of years of tectonic burial, heat and pressure transformed the clay minerals of the sedimentary rock – shale – into the more stable micas of muscovite and chlorite. This new metamorphic rock – slate – the result of the mountain-building activity that created the Taconics and Green Mountains would support an industry stretching from Fair Haven, Vermont to Hoosick Falls, New York.
Slate in Vermont was famously discovered around 1839 when a Welsh émigré, visiting a farm in Fair Haven, kicked over a loose group of stones declaring, “There’s slate there.” By the late nineteenth century, on the heels of a prolonged strike in the Penryn Quarry in Wales, Welsh immigration to Vermont was so great that according to Gwilym Roberts, “…the record book of the old National School in the quarry village of Rachub [Wales]…shows the notation ‘Gone to America’ occurring more and more frequently during the 1880s and 1890s…” (Slate in the Valley)