Slate is soil type described by Tom Stevenson as ‘hard, often dark grey (but can be any colour between brown and bluish grey), fine-grain, plate-like rock formed under pressure from clay, siltstone, shale, and other sediments. It warms up quickly, retains its heat well.’ Wine regions with vineyards on slate soils (of varying types) include the Mosel, Saar, and Ruwer regions in Germany, the Upper or Ober Nahe valley at Nierstein and Nackenheim in Rheinhessen, in a few isolated vineyards in the Rhineland-Palatinate or Pfalz region in western Germany, Alsace, and in the Wachau region of Austria (Stuart Pigott: 1995, p.30). See also slaty-schist.
Tom Stevenson (2011) The Sotheby’s Wine Encyclopedia 5th Edition by Tom Stevenson (Dorling Kindersley, 2011), p.19.
Stuart Pigott, The Wine Atlas of Germany (Mitchell Beazley, 1995).