Biork is a natural Crystal deodorant stock.
The aluminum in crystal deodorant stones is a different type of aluminum, called alum. The most common form is potassium alum, also known as potassium aluminum sulfate.
Potassium alum (and other alums) is a natural mineral salt made up of molecules that are too large to be absorbed by your skin. They form a protective layer on your skin that inhibits the growth of odour-causing bacteria.
Biork™´s crystal deodorant lasts longer than you are used to from other deodorants. In addition, the potassium alum contains important minerals. Of course, all ingredients have been dermatologically tested.