Toned cyanotype query

[Linda Stinchfield <linda@turtlesilk.com>]

I have a book, Photography's Antiquarian Avant-Garde, the New Wave in Old Processes, by Lyle Rexer, and on p. 122 there's an image by John Metoyer that's identified simply as "toned cyanotype". Would anyone on the list be familiar with the book-- and more importantly (to me) what that image might have been toned wth?  The highligts are a purplish gray and the darks are kind of deep indigo. 

Thanks,
Linda S.