Wikipedia
Antimony trioxide
Antimony(III) oxide is the inorganic compound with the formula SbO. It is the most important commercial compound of antimony. It is found in nature as the minerals valentinite and senarmontite. Like most polymeric oxides, SbO dissolves in aqueous solutions with hydrolysis.
Antimony trioxide (data page)
Also Known as Sb2O3. It has a melting point of 656°C, and a boiling point of 1550°C. It is a Cubic Crystal Structure with a density of 5.2G/Cm3
This page provides supplementary chemical data on antimony trioxide.