Slate was extracted from the so called Slate Hills of Kirkney, Corskie, Foudland, Tillymorgan and others in the NE of Scotland. Of these the most important quarries were on the Hill of Foudland and the name Foudland is sometime used as a generic trem for slates from the area. Production started in the 1700s and reached a peak of almost 2 million slates in the mid 19th century. Most of the quarries closed during the second half of the century as the development of railways enabled slate from other parts of Great Britain to be sold competitively in the area.
All of the quarries are located within the Macduff Slate Formation. This Formation outcrops over a large part of the NE of Scotland, from Macduff on the coast, from where it gets its name, to Huntly 50km to the south. However slate has only been quarried as a roofing material in a range of hills just south of Huntly. This is due to the proximity of an igneous intrusion which, due to increased temperatures at the time of emplacement, hardened the surrounding rock. As a result of this hardening, the slate rock forms the high ground, relative to the softer slate to the north.
Macduff slate have a rough gritty texture of a coarse-grained material, rich in quartz. It is possible to see small grains of quartz on the surface. The slates are generally blue-grey in colour often with a purple hue. Unlike Ballachulish and Easdale slate, there is no pyrite present. Instead, the iron ore mineral is an oxide, haematite, which gives the slates a purple colour. The most distinctive property of Macduff slate is “spotting”: small dark specks approximately 0.5 mm in size evenly distributed throughout the slate. These dark spots are mainly chlorite with mica intergrowths along the cleavage.
Macduff slate is still found on the roofs of buildings in the area over a hundred years after production had ceased; a testimony to the durability of the material. The Scottish Stone Liaison Group, in an attempt to find new sources of Scottish slate, selected the Hill of Foudland as one of two locations for the extraction and testing of new slate. In 2003 blocks of rock were extracted and split into slates from one of the Lower Quarries on the Hill ( NJ608337), the first new Macduff slate in over a century. In 2005 this exercise was followed by the extraction of two cores, over 40m in length, from the floor of the quarry in order to assess the resources of slate in the vicinity. (The results of this exercise are recorded in “Macduff Slate; Extraction and testing of slate from the Hill of Foudland, Aberdeenshire.” published by Historic Scotland in 2008.