Hi Gary
Verdaccio. I translate freely from "Pittura murale" Del Giuseppe Ronchetti: "...Take the amount of one big bean of dark Ochre (because there are two kind of Ochre, light and dark); and if you do not have dark take light well ground. Put it in a glass vase, add a little black, mix it. take a little Bianco sangiovanni, approximately one third of a bean; take one point of small knife of light Cinabrese (kind of Terra rossa); Mix them all togather and add clear water without tempera (adhesiv)..." "...This color called in Firenze Verdaccio, in Siena Bazzo..."
Traditionally it was used to line the first pattern of the painting on the Intonaco. With addition of some terra verde it was used for the the first layer of flesh in shading spots with flesh tones on top of it.
Happy Passover
Yoram