What is "sassolite"

n. (context mineralogy English) A volcanic mineral form of boric acid originally found in Sasso, near Volterra in Italy

Sassolite is a borate mineral, and is the mineral form of boric acid. It occurs in volcanic fumaroles and hot springs, as well as in bedded sedimentary evaporite deposits.

Its mineral form was first described in 1800, and was named after Sasso Pisano, Castelnuovo Val di Cecina, Pisa Province, Tuscany, Italy where it was found. The mineral may be found in lagoons throughout Tuscany and Sasso. Usually coloured white to gray, it is colourless in transmitted light, and can also take on a yellow colour from sulfur impurities, or brown from iron oxides.