Note: While it was technically true that elemental iron cannot be acted upon by acuity fields, making weapons or restraints from it in an attempt to control mentats typically failed for two reasons. First, while iron could not be directly acted upon or through by a mentat, it did not stop a mentat from using other materials to indirectly act upon an iron object. Second, creating elementally pure iron is extremely difficult and expensive. Any impurities in the iron would allow it to be acted upon by a mentat with sufficient strength.