Karin Herzog was inspired by the ancient Egyptians, who used a sheer powder to protect themselves from the sun, to make Isis. Herzog's identical formulation has, as its main ingredient, talc. Doubtless ancient Egyptian medical science hadn't equipped them with the knowledge that talc is linked to skin cancer. Here in the 21st Century we know better. The Egyptians certainly knew about mica, another ingredient in Egyptian Earth Isis. Whether they used as a sunscreen is, as far as I can tell, undocumented. The other ingredient is kaolin. I hope Herzog isn't sourcing her kaolin from Egypt as the only one mined there is of inferior quality.
By the way, there is a Mr Herzog. Born nearly a century ago, he invented the artificial respiration system but abandoned such medical mundanity to work at Karin's side producing oxygen-based face cream.