Feldspar | A soil type defined by Tom Stevenson as ‘One of the most common minerals, feldspar is a white- or rose-coloured silicate of either potassium-aluminium or sodium-calcium-aluminium and is present in a number of rocks, including including granite and basalt.’

Bibliography

Tom Stevenson (2011) The Sotheby’s Wine Encyclopedia 5th Edition by Tom Stevenson (Dorling Kindersley, 2011), p.17-19.