Commercial preparationog ZnO is obtained by burning Zn-vapours in air. ZnO is collected as white wooly flocks and hence is called as philosopher's wool.

Properties: It is a white amorphous powder which becomes sulpur-yellow on heating but again white on cooling. It is insoluble in water. It is an amphoteric oxide since, it dissolves radily in acids forming the zinc salt and in alkalies forming zincates.