Iecologic crystal deodorant is 100% alum. It is free from aluminium clorhydrate and aluminium zirconium. These are the aluminums that can be harmful.
Alum is a material made of natural mineral salts, that has bigger molecules than what the skin can absorb. It creates a protecting layer on the skin, so it prevents the spread of bacteria that create odours.
It doesn't clog the pores, so it isn't anti-perspirant. Perspiration is the most natural detoxifing process.
Won't stain clothes. Hypoallergenic.
Application: Water the crystal a little bit, than apply on your armpits. Also ideal as a styptic and as after shave.