Processes are provided for preparing mupirocin calcium dihydrate from pseudomonic acid in a two phase system by using an organic carboxylate.A highly pure composition of amorphous mupirocin calcium is provided, and processes for its preparation by solvent removal, lyophilization and precipitation with use of an anti-solvent. Pharmaceutical compositions of amorphous form, and methods of using them to treat infections are also provided.Also provided are combined processes for preparing mupirocin calcium dihydrate and amorphous, by producing amorphous form first, followed by conversion of amorphous form into the dihydrate through crystallization from an aqueous solution. Also provided are processes for removing the water of crystallization of the dihydrate to obtain mupirocin calcium anhydrate.