the Lacebark Elm also known as the Chinese Elm.
After firing this *should* become a darker brown although I really do love this rusty shade of the unfired stain. I may have to work on figuring a way to get a similar effect...maybe with underglazes.
This elm impression tile is available at http://www.etsy.com/shop/StudioByTheForest. I plan to add some of the pendants, possibly as necklaces in the next week or so!