"Al2S3" refers to aluminum sulfide, which is the formula for a colorless chemical that exists in several forms. It is made up of two atoms of aluminum and 3 atoms of sulfur.
Aluminum sulfide is moderately soluble in water and acid, and is sensitive to moisture. Appearing as a gray solid, it has a trigonal crystal structure, and it has at least six known crystalline forms. It has a melting point of 2,010° Fahrenheit and a boiling point of 2,730° Fahrenheit. Two common synonyms for this compound are dialuminum sulfur and dialuminum trisulphide, It is available in a number of different countries and a variety of volumes.