Noah Webster
Iolite
I'OLITE, noun [Gr. a violet, and stone.] A mineral of a violet blue color, with a shade of purple or black, called also dichroit and cordierite. It occurs in regular six-sided prisms. Its varieties are peliom and steinheilite.
[Note. By the regular principles of pronouncing the Greek iota and the Shemitic jod, this word ought to be pronounced yolite.]