Otter Breastplates were worn by the Plains Indians and were commonly decorated with Trade Mirrors Fur traders introduced Trade Mirrors to the American Indians in the 17th century. Reflective surfaces were thought to have mystical powers and these mirrors were quickly adopted for use as decorative additions to warbonnets, otter breastplates and bustles, as well as for signaling mirrors. See more on My Blog my blog http://khendersonart2.blogspot.com