Basalt material | A soil type which Tom Stevenson (2011) says ‘accounts for as much as 90 per cent of all lava-based volcanic rocks. It contains various minerals, is rich in lime and soda, but not quartz, the most abundant of all minerals, and it is poor in potash.’

Bibliography

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