† 1. = AFTER-WORT. Hence fig. Obs.
1672. Marvell, Reh. Transp., I. 82. His Defence was but the blew-John of his Ecclesiastical Policy, and this Preface the Tap-droppings of his Defence.
1683. Salmon, Doron Med., I. 242. Brewers Afterworts, or Wash, called ‘Blew-John.’
2. A local name of the blue Fluor-spar found in Derbyshire.
1772. Gilpin, Lakes Cumberland (1788), II. 217. It … is known in London by the name of the Derbyshire drop. But on the spot it is called Blue John, from the beautiful blue veins which overspread the finest parts of it.
1840. Humble, Dict. Geol. & Min. (1843), s.v., The blue-john or fluor spar mine near Castleton in Derbyshire.
