Thank you for the question. The tiles are from interceramic tile. They have a metallic sheen, but I don't have the name of the specific tile. If you go to the interceramic website you should be able to find it.
Thank you.

Thank you so very much. I think I found them, Interceramic Tile, Oxide in "Argilla" in 12x24" tiles. I really like this as a wall tile in a powder room. Perfect. Thanks so much again.

You are correct. You can purchase these tiles at http://www.southcypress.com/Flooring/Interceramic-Tile-Oxide/Oxide-11-5-x-23-25-Argilla-Rectified and also view other sizes and options. Through our website you can order samples or you can call and talk to a representative at 1-800-891-2623.

available here in a different format -

https://tiledaily.com/2016/03/15/rustic-metallic-porcelain-tile/

https://tiledaily.com/2013/10/07/antracita-metallic-porcelain-tiles/