iolite Min.
(ˈaɪəlaɪt)
Also yolite, iolithe.
[= Ger. iolith (Werner, 1808), f. Gr. ἴον violet + λίθος stone: see -lite.]
A silicate of aluminium, iron, and magnesium, occurring in short orthorhombic crystals, or granular; of various shades of blue or violet-blue, and commonly showing different colours in different directions; very subject to alteration by exposure, giving rise to many varieties. Also called cordierite or dichroite.
| [1758 Sir J. Hill (title) An Account of a Stone [etc.]..with the History of the Iolithos, or Violet Stone, of the Germans.] 1810 Nicholson's Jrnl. XXVII. 235 The denomination of yolite (violet-stone). 1821 R. Jameson Man. Min. 193 Prismato-Rhomboidal Quartz, or Iolite. 1831 Brewster Optics xxx. 249 M. Cordier observed the same change of colour in a mineral called iolite, to which Haüy gave the name of dichroite. 1868 Dana Min. (ed. 5) §287 Iolite..Lustre vitreous. Pleochroic, being often deep blue along the vertical axis, and brownish yellow or yellowish gray perpendicular to it. |