Cullen stone
Noun
Meaning
(historical) A form of black lava quarried in the Rhine Valley and used for millstones.
(historical) A millstone made from this substance.
Source: en.wiktionary.orgNoun
(historical) A form of black lava quarried in the Rhine Valley and used for millstones.
(historical) A millstone made from this substance.
Source: en.wiktionary.org