Castoreum comes from the scent glands of beavers, and in perfumery it is prized for its rich, leathery, almost smoky warmth. At low doses it smells like worn leather, birch tar and warm animal skin with a sweet, almost fruity undertone. It is the secret behind many classic leather chypres and smoky orientals, giving them that rugged, lived-in depth. Like civet, natural castoreum is now largely replaced by ethical synthetic reconstructions. In India, castoreum-anchored leathers are magnificent in winter, when cool air lets their smoky warmth unfold slowly over hours. They are far too heavy for summer days. If you love the smell of a well-worn leather jacket with a hint of smoke, castoreum is the note creating that effect in your fragrance.