The Collaborative International Dictionary of English v.0.48:

Gismondine \Gis*mon"dine\ (j[i^]s*m[o^]n"d[i^]n), Gismondite
\Gis*mon"dite\ (j[i^]s*m[o^]n"d[imac]t), n. [From the name of
   the discoverer, Gismondi.] (Min.)
   A native hydrated silicate of alumina, lime, and potash,
   first noticed near Rome.
   [1913 Webster]