
1) Borate mineral 2) Luminescent mineral
Found on
https://www.crosswordclues.com/clue/sassolite

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 f...
Found on
http://en.wikipedia.org/wiki/Sassolite

Sassolite (Boric Acid) is a vitreous, white mineral found in volcanic areas and in hot springs. It is named after Sasso in Italy where it was first discovered.
Found on
http://www.probertencyclopaedia.com/browse/HS.HTM
No exact match found.