Mozart Dark Chocolate liqueur (formerly labeled as "Mozart Black") is known as "Pure 87" because it is 87% pure cocoa macerate with the remaining their signature cocoa distillate. That distillate is made from a sugar-cane base rather than the more traditional grain alcohols, giving it a slightly different (and, to many, sweeter) flavor profile. They describe the liqueur as "Taste of fine dry and tartly dark chocolate."
Mozart Distillerie is an Austrian company celebrating one of their greatest composers Wolfgang Amadeus Mozart. It was founded in 1954 specializing in chocolates.