...but wore cloth turbans, and one sported a silver gorget across his chest.
...and draped around his neck on a leather strip, his shell gorget necklace.
Citizens Creek by Lalita Tademy
A gorget is a warrior's neck ornament. According to the SCA, the gorget was a functional defensive collar to protect the throat during sword fights. By the 18th century, the gorget had evolved to a large ornate pendant of little, but decorative/ceremonial, value.
The gorgets above, from a terrific historical novel of 19th century American Indians, were worn by native Americans and made of available materials, chosen for aesthetics and value.
For more on Citizens Creek: http://1book42day.blogspot.com/2014/11/citizens-creek-by-lalita-tademy.html