Iodine crystals are widely available and have the following legitimate uses:
As a derivative used to make chemicals and polymers, sanitation and cleaning compounds, pharmaceuticals, nylon fibers, dyes and ink, and photographic film
As a developer to help crime scene investigators discover latent fingerprints on paper surfaces
As a nutritional supplement in table salt
As a common ingredient in dietary supplements for livestock
As an element in the production of electric light bulbs
As a water purification and swimming pool sanitization chemical
As a topical antiseptic for humans, horses, and cattle after the crystals are made into iodine tincture