Some of the earliest references are to Easdale, from which slate was sent to St Andrews in 1197, and to Glasgow to roof the cathedral also in the 12th century. Reliable records began in 1745 when the Earl of Breadalbane and others
established the Marble and Slate Co of Netherlorn to extract slate from Easdale Island.
As demand increased during the 18th and 19th centuries, the company expanded to neighbouring islands. Slates
were transported by sea around the north coast to all the major towns on the east coast and through the Crinan
Canal to Glasgow and other west coast centres.
Ballachulish is the best known Scottish slate, both in terms of quality and quantity.
Production began at the end of the 17th century and expanded rapidly to overtake the Slate Islands in the 1860s.
The quarries were ideally located close to Loch Leven, which enabled slates to be transported by sea around Scotland.
Highland Boundary slate was produced from a series of quarries just north of the Highland Boundary Fault of which Aberfoyle is the best known.
They are grouped together because of similarities in their geology, but have very different histories.
Proximity to the coast was initially the most important factor limiting production; for example, slates from the island of Bute were reputedly used in the 15th century and from Arran in the 18th century.
With improved communications in the 19th century, sea transport was no longer essential and inland quarries such as Aberfoyle came into their own.
The rise and fall of the Scottish slate industry mirrored that in other parts of Britain. Starting slowly, it reached its zenith around 1900, producing 25-30 million slates per annum.
However the beginning of the 20th century was marked by a depression in the building trade, compounded by a shortage of manpower during two World Wars. While the Welsh and English quarries survived, the Scottish industry could not compete with tiles and imported slate. The Ballachulish quarries closed in 1955 and the remaining quarries in the 1960s.